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Title: Researches on Cellulose - 1895-1900
Author: Bevan, E. J., Cross, C. F.
Language: English
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RESEARCHES ON CELLULOSE
1895-1900
BY
CROSS & BEVAN
(C. F. CROSS AND E. J. BEVAN)
_SECOND EDITION_
LONGMANS, GREEN, AND CO.
39 PATERNOSTER ROW, LONDON
NEW YORK, BOMBAY, AND CALCUTTA
1907
All rights reserved
* * * * *
Transcriber's note:
For Text: A word surrounded by a cedilla such as ~this~ signifies that
the word is bolded in the text. A word surrounded by underscores like
_this_ signifies the word is italics in the text. The italic and bold
markup for single italized letters (such as variables in equations) and
"foreign" abbreviations are deleted for easier reading.
For numbers and equations: Parentheses have been added to clarify
fractions. Underscores before bracketed numbers in equations denote a
subscript. Superscripts are designated with a caret and brackets, e.g.
11.1^{3} is 11.1 to the third power. Greek letters in equations are
translated to their English version.
The sections in the Table of Contents are not used in the actual text.
They have been added for clarity.
Minor typos have been corrected and footnotes moved to the end of the
sections
* * * * *
PREFACE TO SECOND EDITION
This edition is a _reprint_ of the first in response to a continuous
demand for the book. The matter, consisting as it does largely of
records, does not call for any revision, and, as a contribution to the
development of theory, any particular interest which it has is
associated with the date at which it was written.
The volume which has since appeared is the sequel, and aims at an
exposition of the subject "to date".
PREFACE
This volume, which is intended as a supplement to the work which we
published in 1895, gives a brief account of researches which have been
subsequently published, as well as of certain of our own investigations,
the results of which are now for the first time recorded.
We have not attempted to give the subject-matter the form of a connected
record. The contributions to the study of 'Cellulose' which are noticed
are spread over a large area, are mostly 'sectional' in their aim, and
the only cohesion which we can give them is that of classifying them
according to the plan of our original work. Their subject-matter is
reproduced in the form of a _précis_, as much condensed as possible; of
the more important papers the original title is given. In all cases we
have endeavoured to reproduce the Author's main conclusions, and in most
cases without comment or criticism.
Specialists will note that the basis of investigation is still in a
great measure empirical; and of this the most obvious criterion is the
confusion attaching to the use of the very word 'Cellulose.' This is due
to various causes, one of which is the curious specialisation of the
term in Germany as the equivalent of 'wood cellulose.' The restriction
of this general or group term has had an influence even in scientific
circles. Another influence preventing the recognition of the obvious
and, as we think, inevitable basis of classification of the 'celluloses'
is the empiricism of the methods of agricultural chemistry, which as
regards cellulose are so far chiefly concerned with its negative
characteristics and the analytical determination of the indigestible
residue of fodder plants. Physiologists, again, have their own views and
methods in dealing with cellulose, and have hitherto had but little
regard to the work of the chemist in differentiating and classifying the
celluloses on a systematic basis. There are many sides to the subject,
and it is only by a sustained effort towards centralisation that the
general recognition of a systematic basis can be secured.
We may, we hope usefully, direct attention to the conspicuous neglect of
the subject in this country. To the matter of the present volume,
excluding our own investigations, there are but two contributions from
English laboratories. We invite the younger generation of students of
chemistry to measure the probability of finding a working career in
connection with the cellulose industries. They will not find this
invitation in the treatment accorded to the subject in text-books and
lectures. It is probable, indeed, that the impression produced by their
studies is that the industries in coal-tar products largely exceed in
importance those of which the carbohydrates are the basis; whereas the
former are quite insignificant by comparison. A little reflection will
prove that cellulose, starch, and sugar are of vast industrial moment in
the order in which they are mentioned. If it is an open question to
what extent science follows industry, or _vice versa_, it is not open to
doubt that scientific men, and especially chemists, are called in these
days to lead and follow where industrial evolution is most active. There
is ample evidence of activity and great expansion in the cellulose
industries, especially in those which involve the chemistry of the raw
material; and the present volume should serve to show that there is
rapid advance in the science of the subject. Hence our appeal to the
workers not to neglect those opportunities which belong to the days of
small beginnings.
We have especially to acknowledge the services of Mr. J. F. BRIGGS in
investigations which are recorded on pp. 34-40 and pp. 125-133 of the
text.
CONTENTS
THE MATTER OF THIS VOLUME MAY BE DIVIDED INTO THE FOLLOWING SECTIONS
PAGE
INTRODUCTION--DEALING WITH THE SUBJECT IN GENERAL OUTLINE 1
SECTION
I. GENERAL CHEMISTRY OF THE TYPICAL COTTON CELLULOSE 13
II. SYNTHETICAL DERIVATIVES--SULPHOCARBONATES AND ESTERS 27
III. DECOMPOSITIONS OF CELLULOSE SUCH AS THROW LIGHT
ON THE PROBLEM OF ITS CONSTITUTION 67
IV. CELLULOSE GROUP, INCLUDING HEMICELLULOSES AND
TISSUE CONSTITUENTS OF FUNGI 97
V. FURFUROIDS, i.e. PENTOSANES AND FURFURAL-YIELDING
CONSTITUENTS GENERALLY 114
VI. THE LIGNOCELLULOSES 125
VII. PECTIC GROUP 152
VIII. INDUSTRIAL AND TECHNICAL. GENERAL REVIEW 155
INDEX OF AUTHORS 177
INDEX OF SUBJECTS 178
CELLULOSE
INTRODUCTION
In the period 1895-1900, which has elapsed since the original
publication of our work on 'Cellulose,' there have appeared a large
number of publications dealing with special points in the chemistry of
cellulose. So large has been the contribution of matter that it has been
considered opportune to pass it under review; and the present volume,
taking the form of a supplement to the original work, is designed to
incorporate this new matter and bring the subject as a whole to the
level to which it is thereby to be raised. Some of our critics in
reviewing the original work have pronounced it 'inchoate.' For this
there are some explanations inherent in the matter itself. It must be
remembered that every special province of the science has its systematic
beginning, and in that stage of evolution makes a temporary 'law unto
itself.' In the absence of a dominating theory or generalisation which,
when adopted, gives it an organic connection with the general advance of
the science, there is no other course than to classify the
subject-matter. Thus 'the carbohydrates' may be said to have been in the
inchoate condition, qualified by a certain classification, prior to the
pioneering investigations of Fischer. In attacking the already
accumulated and so far classified material from the point of view of a
dominating theory, he found not only that the material fell into
systematic order and grew rapidly under the stimulus of fruitful
investigation, but in turn contributed to the firmer establishment of
the theoretical views to which the subject owed its systematic new
birth. On the other hand, every chemist knows that it is only the
simpler of the carbohydrates which are so individualised as to be
connoted by a particular formula in the stereoisomeric system. Leaving
the monoses, there is even a doubt as to the constitution of cane sugar;
and the elements of uncertainty thicken as we approach the question of
the chemical structure of starch. This unique product of plant life has
a literature of its own, and how little of this is fully known to what
we may term the 'average chemist' is seen by the methods he will employ
for its quantitative estimation. In one particular review of our work
where we are taken to task for producing 'an aggravating book, inchoate
in the highest degree ... disfigured by an obscurity of diction which
must materially diminish its usefulness' ['Nature,' 1897, p. 241], the
author, who is a well-known and competent critic, makes use of the short
expression in regard to the more complex carbohydrates, 'Above cane
sugar, higher in the series, all is chaos,' and in reference to starch,
'the subject is still enshrouded in mystery.' This 'material' complexity
is at its maximum with the most complex members of the series, which are
the celluloses, and we think accounts in part for the impatience of our
critic. 'Obscurity of diction' is a personal quantity, and we must leave
that criticism to the fates. We find also that many workers whose
publications we notice in this present volume quite ignore the _plan_ of
the work, though they make use of its matter. We think it necessary to
restate this plan, which, we are satisfied, is systematic, and, in fact,
inevitable. Cellulose is in the first instance a _structure_, and the
anatomical relationships supply a certain basis of classification. Next,
it is known to us and is defined by the negative characteristics of
resistance to hydrolytic actions and oxidations. These are dealt with in
the order of their intensity. Next we have the more positive definition
by ultimate products of hydrolysis, so far as they are known, which
discloses more particularly the presence of a greater or less proportion
of furfural-yielding groups. Putting all these together as criteria of
function and composition we find they supply common or general dividing
lines, within which groups of these products are contained. The
classification is natural, and in that sense inevitable; and it not only
groups the physiological and chemical facts, but the industrial also. We
do not propose to argue the question whether the latter adds any cogency
to a scientific scheme. We are satisfied that it does, and we do not
find any necessity to exclude a particular set of phenomena from
consideration, because they involve 'commercial' factors. We have dealt
with this classification in the original work (p. 78), and we discuss
its essential basis in the present volume (p. 28) in connection with the
definition of a 'normal' cellulose. But the 'normal' cellulose is not
the only cellulose, any more than a primary alcohol or an aliphatic
alcohol are the only alcohols. This point is confused or ignored in
several of the recent contributions of investigators. It will suffice to
cite one of these in illustration. On p. 16 we give an account of an
investigation of the several methods of estimating cellulose, which is
full of valuable and interesting matter. The purpose of the author's
elaborate comparative study is to decide which has the strongest claims
to be regarded as the 'standard' method. They appear to have a
preference for the method of Lange--viz. that of heating at high
temperatures (180°) with alkaline hydrates, but the investigation shows
that (as we had definitely stated in our original work, p. 214) this is
subject to large and variable errors. The adverse judgment of the
authors, we may point out, is entirely determined on the question of
aggregate weight or yield, and without reference to the ultimate
composition or constitution of the final product. None of the available
criteria are applied to the product to determine whether it is a
cellulose (anhydride) or a hydrate or a hydrolysed product. After these
alkali-fusion processes the method of chlorination is experimentally
reviewed and dismissed for the reason that the product retains
furfural-yielding groups, which is, from our point of view, a particular
recommendation, i.e. is evidence of the selective action of the chlorine
and subsequent hydrolysis upon the lignone group. As a matter of fact it
is the only method yet available for isolating the cellulose from a
lignocellulose by a treatment which is quantitatively to be accounted
for in every detail of the reactions. It does not yield a 'normal'
cellulose, and this is the expression which, in our opinion, the authors
should have used. It should have been pointed out, moreover, that, as
the cellulose is separated from actual condensed combination with the
lignone groups, it may be expected to be obtained in a hydrated form,
and also not as a homogeneous substance like the normal cotton
cellulose. The product is a cellulose of the second group of the
classification. Another point in this investigation which we must
criticise is the ultimate selection of the Schulze method of prolonged
maceration with nitric acid and a chlorate, followed by suitable
hydrolysis of the non-cellulose derivatives to soluble products. Apart
from its exceptional inconvenience, rendering it quite impracticable in
laboratories which are concerned with the valuation of cellulosic raw
materials for industrial purposes, the attack of the reagent is complex
and ill-defined. This criticism we would make general by pointing out
that such processes quite ignore the specific characteristics of the
non-cellulose components of the compound celluloses. The second division
of the plan of our work was to define these constituents by bringing
together all that had been established concerning them. These groups are
widely divergent in chemical character, as are the compound celluloses
in function in the plant. Consequently there is for each a special
method of attack, and it is a reversion to pure empiricism to expect any
one treatment to act equally on the pectocelluloses, lignocelluloses,
and cutocelluloses. Processes of isolating cellulose are really more
strictly defined as methods of selective and regulated attack of the
groups with which they occur, combined or mixed. A chemist familiar with
such types as rhea or ramie (pectocellulose), jute (lignocellulose), and
raffia (cutocellulose) knows exactly the specific treatment to apply to
each for isolating the cellulose, and must view with some surprise the
appearance at this date of such 'universal prescriptions' as the process
in question.
The third division of our plan of arrangement comprised the synthetical
derivatives of the celluloses, the sulphocarbonates first, as peculiarly
characteristic, and then the esters, chiefly the acetates, benzoates,
and nitrates. To these, investigators appear to have devoted but little
attention, and the contribution of new matter in the present volume is
mainly the result of our own researches. It will appear from this work
that an exhaustive study of the cellulose esters promises to assist very
definitely in the study of constitutional problems.
This brings us to the fourth and, to the theoretical chemist, the most
important aspect of the subject, the problem of the actual molecular
structure of the celluloses and compound celluloses. It is herein we are
of opinion that the subject makes a 'law unto itself.' If the
constitution of starch is shrouded in mystery and can only be vaguely
expressed by generalising a complex mass of statistics of its successive
hydrolyses, we can only still more vaguely guess at the distance which
separates us from a mental picture of the cellulose unit. We endeavour
to show by our later investigations that this problem merges into that
of the actual structure of cellulose in the mass. It is definitely
ascertained that a change in the molecule, or reacting unit, of a
cellulose, proportionately affects the structural properties of the
derived compounds, both sulphocarbonates and esters. This is at least an
indication that the properties of the visible aggregates are directly
related to the actual configuration of the chemical units. But it
appears that we are barred from the present discussion of such a problem
in absence of any theory of the solid state generally, but more
particularly of those forms of matter which are grouped together as
'colloids.'
Cellulose is distinguished by its inherent constructive functions, and
these functions take effect in the plastic or colloidal condition of the
substance. These properties are equally conspicuous in the synthetical
derivatives of the compound. Without reference, therefore, to further
speculations, and not deterred by any apparent hopelessness of solving
so large a problem, it is clear that we have to exhaust this field by
exact measurements of all the constants which can be reduced to
numerical expression. It is most likely that the issue may conflict with
some of our current views of the molecular state which are largely drawn
from a study of the relatively dissociated forms of matter. But such
conflicts are only those of enlargement, and we anticipate that all
chemists look for an enlargement of the molecular horizon precisely in
those regions where the forces of cell-life manifest themselves.
The _cellulose group_ has been further differentiated by later
investigations. The fibrous celluloses of which the typical members
receive important industrial applications, graduate by insensible stages
into the hemicelluloses which may be regarded as a well-established
sub-group. In considering their morphological and functional
relationships it is evident that the graduation accords with their
structure and the less permanent functions which they fulfil. They are
aggregates of monoses of the various types, chiefly mannose, galactose,
dextrose, &c., so far as they have been investigated.
Closely connected with this group are the constituents of the tissues of
fungi. The recent researches of Winterstein and Gilson, which are noted
in this present volume, have established definitely that they contain a
nitrogenous group in intimate combination with a carbohydrate complex.
This group is closely related to chitin, yielding glucosamin and acetic
acid as products of ultimate hydrolysis. Special interest attaches to
these residues, as they are in a sense intermediate products between the
great groups of the carbohydrates and proteids (E. Fischer, Ber. 19,
1920), and their further investigation by physiological methods may be
expected to disclose a genetic connection.
The _lignocelluloses_ have been further investigated. Certain new types
have been added, notably a soluble or 'pectic' form isolated from the
juice of the white currant (p. 152), and the pith-like wood of the
Æschynomene (p. 135).
Further researches on the typical fibrous lignocellulose have given us a
basis for correcting some of the conclusions recorded in our original
work, and a study of the esters has thrown some light on the
constitution of the complex (p. 130).
Of importance also is the identification of the hydroxyfurfurals as
constituents of the lignocelluloses generally, and the proof that the
characteristic colour-reactions with phenols (phloroglucinol) may be
ascribed to the presence of these compounds (p. 116).
The _pectocelluloses_ have not been the subject of systematic chemical
investigation, but the researches of Gilson ('La Cristallisation de la
Cellulose et la Composition Chimique de la Membrane Cellulaire
Végétale,' 'La Revue,' 'La Cellule,' i. ix.) are an important
contribution to the natural history of cellulose, especially in relation
to the 'pectic' constituents of the parenchymatous celluloses.
Indirectly also the researches of Tollens on the 'pectins' have
contributed to the subject in correcting some of the views which have
had a text-book currency for a long period. These are dealt with on p.
151. The results establish that the pectins are rather the soluble
hydrated form of cellulosic aggregates in which acid groups may be
represented; but such groups are not to be regarded as essentially
characteristic of this class of compounds.
~Furfural-yielding Substances~ (Furfuroids).--This group of plant products
has been, by later investigations, more definitely and exclusively
connected with the celluloses--i.e. with the more permanent of plant
tissues. From the characteristic property of yielding furfural, which
they have in common with the pentoses, they have been assumed to be the
anhydrides of these C_{5} sugars or pentosanes; but the direct evidence
for this assumption has been shown to be wanting. In regard to their
origin the indirect evidences which have accumulated all point to their
formation in the plant from hexoses. Of special interest, in its
bearings on this point, is the direct transformation of levulose into
furfural derivatives, which takes place under the action of condensing
agents. The most characteristic is that produced by the action of
anhydrous hydrobromic acid in presence of ether [Fenton], yielding a
brommethyl furfural
C_{6}H_{12}O_{6} - 4H_{2}O + HBr = C_{5}H_{3}.O_{2}.CH_{2}Br
with a Br atom in the methyl group. These researches of Fenton's appear
to us to have the most obvious and direct bearings upon the genetic
relationships of the plant furfuroids and not only _per se_. To give
them their full significance we must recall the later researches of
Brown and Morris, which establish that cane sugar is a primary or direct
product of assimilation, and that starch, which had been assumed to be a
species of universal _matière première_, is probably rather a general
reserve for the elaborating work of the plant. If now the aldose groups
tend to pass over into the starch form, representing a temporary
overflow product of the assimilating energy, it would appear that the
ketose or levulose groups are preferentially used up in the elaboration
of the permanent tissue. We must also take into consideration the
researches of Lobry de Bruyn showing the labile functions of the typical
CO group in both aldoses and hexoses, whence we may conclude that in the
plant-cell the transition from dextrose to levulose is a very simple and
often occurring process.
We ourselves have contributed a link in this chain of evidence
connecting the furfuroids of the plant with levulose or other
keto-hexose. We have shown that the hydroxyfurfurals are constituents of
the lignocelluloses. The proportion present in the free state is small,
and it is not difficult to show that they are products of breakdown of
the lignone groups. If we assume that such groups are derived ultimately
from levulose, we have to account for the detachment of the methyl
group. This, however, is not difficult, and we need only call to mind
that the lignocelluloses are characterised by the presence of methoxy
groups and a residue which is directly and easily hydrolysed to acetic
acid. Moreover, the condensation need not be assumed to be a simple
dehydration with attendant rearrangement; it may very well be
accompanied or preceded by fixation of oxygen. Leaving out the
hypothetical discussion of minor variations, there is a marked
convergence of the evidence as to the main facts which establish the
general relationships of the furfuroid group. This group includes both
saturated and unsaturated or condensed compounds. The former are
constituents of celluloses, the latter of the lignone complex of the
lignocelluloses.
The actual production of furfural by boiling with condensing acids is a
quantitative measure of only a portion, i.e. certain members of the
group. The hydroxyfurfurals, not being volatile, are not measured in
this way. By secondary reactions they may yield some furfural, but as
they are highly reactive compounds, and most readily condensed, they are
for the most part converted into complex 'tarry' products. Hence we have
no means, as yet, of estimating those tissue constituents which yield
hydroxyfurfurals; also we have no measure of the furfurane-rings
existing performed in such a condensed complex as lignone. But, chemists
having added in the last few years a large number of facts and
well-defined probabilities, it is clear that the further investigation
of the furfuroid group will take its stand upon a much more adequate
basis than heretofore. On the view of 'furfural-yielding' being
co-extensive with 'pentose or pentosane,' not only were a number of
important facts obscured or misinterpreted, but there was a barrenness
of suggestion of genetic relationships. As the group has been widened
very much beyond these limits, it is clear that if any group term or
designation is to be retained that of 'furfuroid' is 'neutral' in
character, and equally applicable to saturated substances of such widely
divergent chemical character as pentoses, hexosones, glycuronic acid,
and perhaps, most important of all, levulose itself, all of which are
susceptible of condensation to furfural or furfurane derivatives, as
well as to those unsaturated compounds, constituents of plant tissues
which are already furfurane derivatives.
From the chemical point of view such terms are perhaps superfluous. But
physiological relationships have a significance of their own; and there
is a physiological or functional cohesion marking this group which
calls for recognition, at least for the time, and we therefore propose
to retain the term furfuroid.[1]
~General Experimental Methods.~--In the investigation of the cellulose
group it is clear that methods of ultimate hydrolysis are of first
importance. None are so convenient as those which are based on the
action of sulphuric acid, more or less concentrated (H_{2}SO_{4}.3H_{2}O
- H_{2}SO_{4}H_{2}O). Such methods have been frequently employed in the
investigations noted in this volume. We notice a common deficiency in
the interpretation of the results. It appears to be sufficient to
isolate and identify a crystalline monose, without reference to the
yield or proportion to the parent substance, to establish some main
point in connection with its constitution. On the other hand, it is
clear that in hydrolysing a given cellulose-complex we ought to aim at
complete, i.e. _quantitative, statistics_. The hydrolytic transformation
of starch to dextrins and maltose has been followed in this way, and the
methods may serve as a model to which cellulose transformations should
be approximated. In fact, what is very much wanted is a systematic
re-examination of the typical celluloses in which all the constants of
the terms between the original and the ultimate monose groups shall be
determined. Such constants are similar to those for the starch-dextrose
series, viz. opticity and cupric reduction. Various methods of
fractionation are similarly available, chiefly the precipitation of the
intermediate 'dextrins' by alcohol.
Where the original celluloses are homogeneous we should thus obtain
transformation series, similarly expressed to those of starch. In the
case of the celluloses which are mixtures, or of complex constitution,
there are various methods of either fractionating the original, or of
selectively attacking particular monoses resulting from the
transformation. By methods which are approximately quantitative a
mixture of groups, such as we have, for instance, in jute cellulose,
could be followed through the several stages of their resolution into
monoses. To put the matter generally, in these colloidal and complex
carbohydrates the ordinary physical criteria of molecular weight are
wanting. Therefore, we cannot determine the relationship of a given
product of decomposition to the parent molecule save by means of a
quantitative mass-proportion. Physical criteria are only of determining
value when associated with such constants as cupric reduction, and
these, again, must be referred to some arbitrary initial weight, such
as, for convenience, 100 parts of the original.
Instead of adopting these methods, without which, as a typical case, the
mechanism of starch conversions could not have been followed, we have
been content with a purely qualitative study of the analogous series
obtainable from the celluloses under the action of sulphuric acid. A
very important field of investigation lies open, especially to those who
are generally familiar with the methods of studying starch conversions;
and we may hope in this direction for a series of valuable contributions
to the problem of the actual constitution of the celluloses.
FOOTNOTES:
[1] In this we are confirmed by other writers. See Tollens, _J. für
Landw._ 1901, p. 27.
SECTION I. GENERAL CHEMISTRY OF THE TYPICAL COTTON CELLULOSE
(p. 3)[2] ~Ash Constituents.~--It is frequently asserted that silica has a
structural function _sui generis_ in the plant skeleton, having a
relationship to the cellulosic constituents of the plant, distinct from
that of the inorganic ash components with which it is associated. It
should be noted that the matter has been specifically investigated in
two directions. In Berl. Ber. 5, 568 (A. Ladenburg), and again in 11,
822 (W. Lange), appear two papers 'On the Nature of Plant Constituents
containing Silicon,' which contain the results of experimental
investigations of equisetum species--distinguished for their
exceptionally high 'ash' with large proportion of silica--to determine
whether there are any grounds for assuming the existence of
silicon-organic compounds in the plant, the analogues of carbon
compounds. The conclusions arrived at are entirely negative. In
reference to the second assumption that the cuticular tissues of cereal
straws, of esparto, of the bamboo, owe their special properties to
siliceous components, it has been shown by direct experiment upon the
former that their rigidity and resistance to water are in no way
affected by cultivation in a silica-free medium. In other words, the
structural peculiarities of the gramineæ in these respects are due to
the physical characteristics chiefly of the (lignified) cells of the
hypodermal tissue, and to the composition and arrangement of the cells
of the cuticle.
_'Swedish' filter papers_ of modern make are so far freed from inorganic
constituents that the weight of the ash may be neglected in nearly all
quantitative experiments [Fresenius, Ztschr. Anal Chem. 1883, 241]. It
represents usually about 1/1000 mgr. per 1 sq. cm. of area of the paper.
_The form of an 'ash'_ derived from a fibrous structure, is that of the
'organic' original, more or less, according to its proportion and
composition. The proportion of 'natural ash' is seldom large enough, nor
are the components of such character as to give a coherent ash, but if
in the case of a fibrous structure it is combined or intimately mixed
with inorganic compounds deposited within the fibres from solution, the
latter may be made to yield a perfect skeleton of the fibre after
burning off the organic matter. It is by such means that the mantles
used in the Welsbach system of incandescent lighting are prepared. A
purified cotton fabric--or yarn--is treated with a concentrated solution
of the mixed nitrates of thorium and cerium, and, after drying, the
cellulose is burned away. A perfect and coherent skeleton of the fabric
is obtained, composed of the mixed oxides. Such mantles have fulfilled
the requirements of the industry up to the present time, but later
experiments forecast a notable improvement. It has been found that
artificial cellulose fibres can be spun with solutions containing
considerable proportions of soluble compounds of these oxides. Such
fibres, when knitted into mantles and ignited, yield an inorganic
skeleton of the oxides of homogeneous structure and smooth contour. De
Mare in 1894, and Knofler in 1895, patented methods of preparing such
cellulose threads containing the salts of thorium and cerium, by
spinning a collodion containing the latter in solution. When finally
ignited, after being brought into the suitable mantle form, there
results a structure which proves vastly more durable than the original
Welsbach mantle. The cause of the superiority is thus set forth by V.
H. Lewes in a recent publication (J. Soc. of Arts, 1900, p. 858): 'The
alteration in physical structure has a most extraordinary effect upon
the light-giving life of the mantle, and also on its strength, as after
burning for a few hundred hours the constant bombardment of the mantle
by dust particles drawn up by the rush of air in the chimney causes the
formation of silicates on the surface of the mantle owing to silica
being present in the air, and this seems to affect the Welsbach
structure far more than it does the "Clamond" type, with the result that
when burned continuously the Welsbach mantle falls to so low a pitch of
light emissivity after 500 to 600 hours, as to be a mere shadow of its
former self, giving not more than one-third of its original light,
whilst the Knofler mantle keeps up its light-emitting power to a much
greater extent, and the Lehner fabric is the most remarkable of all. Two
Lehner mantles which have now been burning continuously in my laboratory
for over 3,000 hours give at this moment a brighter light emissivity
than most of the Welsbachs do in their prime.' ...'The new developments
of the Clamond process form as important a step in the history of
incandescent gas lighting as the discoveries which gave rise to the
original mantles.'
It has further been found that the oxides themselves can be dissolved in
the cellulose alkaline sulphocarbonate (viscose) solution, and
artificial threads have been spun containing from 25 to 30 p.ct. of the
oxides in homogeneous admixture with the cellulose. This method has
obvious advantages over the collodion method both in regard to the
molecular relationship of the oxides to the cellulose and to cheapness
of production.
UNTERSUCHUNGEN ÜBER VERSCHIEDENE BESTIMMUNGSMETHODEN DER CELLULOSE.
H. SURINGAR AND B. TOLLENS (Ztschr. angew. Chem. 1896, No. 23).
~INVESTIGATION OF METHODS OF DETERMINING CELLULOSE.~
_Introduction._--This is an exhaustive bibliography of the subject,
describing also the various methods of cellulose estimation, noted in
historical sequence. First, the Weende 'crude fibre' method (Henneberg)
with modifications of Wattenberg, Holdefleiss, and others is dealt with.
The product of this treatment, viz. 'crude fibre' is a mixture,
containing furfuroids and lignone compounds. Next follows a group of
processes which aim at producing a 'pure cellulose' by eliminating
lignone constituents, for which the merely hydrolytic treatments of the
Weende method are ineffectual. The method of F. Schulze--prolonged
digestion with dilute nitric acid, with addition of chlorate--has been
largely employed, though the composition of the product is more or less
divergent from a 'pure cellulose.'
Dilute nitric acid at 60-80° (Cross and Bevan) and a dilute mixture of
nitric and sulphuric acids (Lifschutz) have been employed for isolating
cellulose from the lignocelluloses. Hoffmeister modifies the method of
Schulze by substituting hydrochloric acid for the nitric acid. Treatment
with the halogens associated with alkaline processes of hydrolysis is
the basis of the methods of Hugo Muller (bromine water) and Cross and
Bevan (chlorine gas). Lastly, the authors notice the methods based upon
the action of the alkaline hydrates at high temperatures (180°) in
presence of water (Lange), or of glycerin (Gabriel). The process of
heating to 210° with glycerin only (Hönig) yields a very impure and
ill-defined product.
For comparative investigation of these processes certain celluloses and
cellulosic materials were prepared as follows:
(a) _'Rag' cellulose._--A chemical filter paper, containing only
cotton and linen celluloses, was further purified by boiling with dilute
acid and dilute alkali. After thorough washing it was air-dried.
(b) _Wood cellulose._--Pine wood sawdust was treated by digestion for
fourteen days with dilute nitric acid with addition of chlorate
(Schulze). The mass was washed and digested with alkaline lye (1.25
p.ct. KOH), and exhaustively washed, treated with dilute acetic acid;
again washed, and finally air-dried.
This product was found to yield 2.3 p.ct. furfural on distillation with
HCl (1.06 sp.gr.).
(c) _Purified wood._--Pine wood sawdust was treated in succession with
dilute alkalis and acids, in the cold, and with alcohol and ether until
exhausted of products soluble in these liquids and reagents.
In addition to the above the authors have also employed jute fibre and
raw cotton wool in their investigations.
They note that the yield of cellulose is in many cases sensibly lowered
by treating the material after drying at the temperature of 100°. The
material for treatment is therefore weighed in the air-dry condition,
and a similar sample weighed off for drying at 100° for determination of
moisture.
The main results of the experimental investigation are as follows:--
_Weende process_ further attacks the purified celluloses as follows:
Wood cellulose losing in weight 8-9 p.ct.; filter paper, 6-7.5 p.ct.,
and the latter treated a second time loses a further 4-5 p.ct. It is
clear, therefore, that the process is of purely empirical value.
_Schulze._--This process gave a yield of 47.6 p.ct. cellulose from pine
wood. The celluloses themselves, treated by the process, showed losses
of 1-3 p.ct. in weight, much less therefore than in the preceding case.
_Hönig's_ method of heating with glycerin to 210° was found to yield
products very far removed from 'cellulose.' The process may have a
certain value in estimations of 'crude fibre,' but is dismissed from
further consideration in relation to cellulose.
_Lange._--The purpose of the investigation was to test the validity of
the statement that the celluloses are not attacked by alkaline hydrates
at 180°. Experiments with pine wood yielded a series of percentages for
cellulose varying from 36 to 41; the 'purified wood' gave also variable
numbers, 44 to 49 per cent. It was found possible to limit these
variations by altering the conditions in the later stages of isolating
the product; but further experiments on the celluloses themselves
previously isolated by other processes showed that they were profoundly
and variably attacked by the 'Lange' treatment, wood cellulose losing 50
per cent. of its weight, and filter paper (cellulose) losing 15 per
cent. Further, a specimen of jute yielded 58 per cent. of cellulose by
this method instead of the normal 78 per cent. It was also found that
the celluloses isolated by the process, when subjected to a second
treatment, underwent a further large conversion into soluble
derivatives, and in a third treatment further losses of 5-10 per cent
were obtained. The authors attach value, notwithstanding, to the process
which they state to yield an 'approximately pure cellulose,' and they
describe a modified method embodying the improvements in detail
resulting from their investigation.
_Gabriel's_ method of heating with a glycerin solution of alkaline
hydrate is a combination of 'Hönig' and 'Lange.' An extended
investigation showed as in the case of the latter that the
celluloses themselves are more or less profoundly attacked by the
treatment--further that the celluloses isolated from lignocelluloses and
other complex raw materials are much 'less pure' than those obtained by
the Lange process. Thus, notably in regard to furfural yielding
constituents, the latter yield 1-2 p.ct. furfural, whereas _specimens of
'jute cellulose'_ obtained by the Gabriel process were found to yield _9
to 13 p.ct. furfural_.
_Cross and Bevan._--Chlorination process yielded in the hands of the
authors results confirming the figures given in 'Cellulose' for yield of
cellulose. Investigation of the products for yield of furfural, gave 9
p.ct. of this aldehyde showing the presence of celluloses, other than
the normal type.
_Conclusions._--The subjoined table gives the mean numerical results for
yield of end-product or 'cellulose' by the various methods. In the case
of the 'celluloses' the results are those of the further action of the
several processes on the end-product of a previous process.
| Methods
| F. Schulze | Weende | Lange | Gabriel | Cross
| | | | | and Bevan
--------------------------------------------------------------------------
Wood cellulose | 98.51 | 91.52 | 48.22 | 55.93 | --
Filter paper cellulose | 99.62 | 95.63 | 78.17 | 79.77 | --
Swedish filter paper | 96.58 | -- | 84.76 | -- | --
Ordinary filter paper | 98.17 | 93.39 | 86.58 | -- | --
Cotton ('wool') | 98.38 | 89.98 | 63.96 | 67.88 | --
Jute | -- | -- | 57.93 | 71.64 | 75.27
Purified wood | -- | -- |{49.27 | -- | --
| | |{46.56 | |
Raw wood | 47.60 | -- |{40.82 | -- | --
| | |{38.87 | |
--------------------------------------------------------------------------
The final conclusion drawn from the results is that none of the
processes fulfil the requirements of an ideal method. Those which may
be carried out in a reasonably short time are deficient in two
directions: (1) they yield a 'cellulose' containing more or less
oxycellulose; (2) the celluloses themselves are attacked under the
conditions of treatment, and the end product or cellulose merely
represents a particular and at the same time variable equilibrium, as
between the resistance of the cellulose and the attack of the reagents
employed; this attack being by no means confined to the non-cellulose
constituents. Schulze's method appears to give the nearest approximation
to the 'actual cellulose' of the raw material.
* * * * *
(p. 8) ~SOLUTIONS OF CELLULOSE~--(1) ~ZINC CHLORIDE.~--To prepare a
homogeneous solution of cellulose by means of the neutral chloride, a
prolonged digestion at or about 100° with the concentrated reagent is
required. The dissolution of the cellulose is not a simple phenomenon,
but is attended with hydrolysis and a certain degree of condensation.
The latter result is evidenced by the formation of furfural, the former
by the presence of soluble carbohydrates in the solution obtained by
diluting the original solution and filtering from the reprecipitated
cellulose. The authors have observed that in carefully conducted
experiments cotton cellulose may be dissolved in the reagent, and
reprecipitated with a loss of only 1 p.ct. in weight. This, however, is
a 'net' result, and leaves undetermined the degree of hydration of the
recovered cellulose as of hydrolysis of the original to groups of lower
molecular weights. Bronnert finds that a previous hydration of the
cellulose--e.g. by the process of alkaline mercerisation and removal of
the alkali by washing--enables the zinc chloride to effect its
dissolution by digestion in the cold. (U.S. patent, 646,799/1900. See
also p. 59.)
_Industrial applications._--(a) _Vulcanised fibre_ is prepared by
treating paper with four times its weight of the concentrated aqueous
solution (65-75° B.), and in the resulting gelatinised condition is
worked up into masses, blocks, sheets, &c., of any required thickness.
The washing of these masses to remove the zinc salt is a very lengthy
operation.
To render the product waterproof the process of nitration is sometimes
superadded [D.R.P. 3181/1878]. Further details of manufacture are given
in Prakt. Handbuch d. Papierfabrikation, p. 1703 [C. Hofmann].
(b) _Calico-printing._--The use of the solution as a thickener or
colour vehicle, more especially as a substitute for albumen in pigment
styles, was patented by E. B. Manby, but the process has not been
industrially developed [E.P. 10,466/1894].
(c) _Artificial silk._--This is a refinement of the earlier
applications of the solution in spinning cellulose threads for
conversion into carbon filaments for electrical glow-lamps. This section
will be found dealt with on p. 59.
(p. 13) (2) ~Cuprammonium solution.~--The application of the solution of
cellulose in cuprammonium to the production of a fine filament in
continuous length, 'artificial silk,' has been very considerably studied
and developed in the period 1897-1900, as evidenced by the series of
patents of Fremery and Urban, Pauly, Bronnert, and others. The subject
will also be found dealt with on p. 58.
* * * * *
(p. 15) ~Reactions of cellulose with iodine.~--In a recent paper, F.
Mylius deals with the reaction of starch and cellulose with iodine,
pointing out that the blue colouration depends upon the presence of
water and iodides. In absence of the latter, and therefore in presence
of compounds which destroy or absorb hydriodic acid--e.g. iodic
acid--there results a _brown_ addition product. The products in question
have the characteristics of _solid solutions_ of the halogen. (Berl.
Ber. 1895, 390.)
(24) ~Mercerisation~--Notwithstanding the enormous recent developments in
the industrial application of the mercerising reaction, there have been
no noteworthy contributions to the theoretical aspects of the subject.
The following abstract gives an outline of the scope of an important
technical work on the subject.
DIE MERCERISATION DER BAUMWOLLE.
PAUL GARDNER (Berlin: 1898. J. Springer).
~THE MERCERISATION OF COTTON.~
This monograph of some 150 pages is chiefly devoted to the patent
literature of the subject. The chemical and physical modifications of
the cotton substance under the action of strong alkaline lye, were set
forth by Mercer in 1844-5, and there has resulted from subsequent
investigations but little increase in our knowledge of the fundamental
facts. The treatment was industrially developed by Mercer in certain
directions, chiefly (1) for preparing webs of cloth required to stand
considerable strain, and (2) for producing crêpon effects by local or
topical action of the alkali. But the results achieved awakened but a
transitory interest, and the matter passed into oblivion; so much so,
indeed, that a German patent [No. 30,966] was granted in 1884 to the
Messrs. Depouilly for crêpon effects due to the differential shrinkage
of fabrics under mercerisation, by processes and treatments long
previously described by Mercer. Such effects have had a considerable
vogue in recent years, but it was not until the discovery of the
lustreing effect resulting from the association of the mercerising
actions with the condition of strain or tension of the yarn or fabric
that the industry in 'mercerised' goods was started on the lines which
have led to the present colossal development. The merit of this
discovery is now generally recognised as belonging to Thomas and Prevost
of Crefeld, notwithstanding that priority of patent right belongs to the
English technologist, H. A. Lowe.
The author critically discusses the grounds of the now celebrated patent
controversy, arising out of the conflict of the claims of German patent
85,564/1895 of the former, and English patent 4452/1890 of the latter.
The author concludes that Lowe's specification undoubtedly describes the
lustreing effect of mercerising in much more definite terms than that of
Thomas and Prevost. These inventors, on the other hand, realised the
effect industrially, which Lowe certainly failed to do, as evidenced by
his allowing the patent to lapse. As an explanation of his failure, the
author suggests that Lowe did not sufficiently extend his observations
to goods made from Egyptian and other long-stapled cottons, in which
class only are the full effects of the added lustre obtained.
Following these original patents are the specifications of a number of
inventions which, however, are of insignificant moment so far as
introducing any essential variation of the mercerising treatment.
The third section of the work describes in detail the various mechanical
devices which have been patented for carrying out the treatment on yarn
and cloth.
The fourth section deals with the fundamental facts underlying the
process and effects summed up in the term 'mercerisation.' These are as
follows:--
(a) Although all forms of fibrous celluloses are similarly affected by
strong alkaline solutions, it is only the Egyptian and other
long-stapled cottons--i.e. the goods made from them--which under the
treatment acquire the special high lustre which ranks as 'silky.' Goods
made from American cottons acquire a certain 'finish' and lustre, but
the effects are not such as to have an industrial value--i.e. a value
proportional to the cost of treatment.
(b) The lustre is determined by exposing the goods to strong tension,
either when under the action of the alkali, or subsequently, but only
when the cellulose is in the special condition of hydration which is the
main chemical effect of the mercerising treatment.
(c) The degree of tension required is approximately that which opposes
the shrinkage in dimensions, otherwise determined by the action of the
alkali. The following table exhibits the variations of shrinkage of
Egyptian when mercerised without tension, under varying conditions as
regards the essential factors of the treatment--viz. (1) concentration
of the alkaline lye, (2) temperature, and (3) duration of action (the
latter being of subordinate moment):--
_______________________________________________________________________
| | | | | |
| Concentration | | | | |
| of lye (NaOH) | 5°B. | 10°B. | 15°B | 25°B |
| | | | | | | | | | | |
| Duration of | | | | | | | | | | |
| action in | 1 | 10 | 30 | 1 | 10 | 30 | 1 | 10 | 30 | |
| minutes | | | | | | | | | | |
| | | | | | | | | | | |
| Temperatures | Percentage shrinkages (Egyptian yarns) as under:-- |
| as under:-- | | | | | | | | | | |
| 2° | 0 | 0 | 0 | 1 | 1 | 1 | 12.2 | 15.2 | 15.8 | 19.2 |
| 18° | 0 | 0 | 0 | 0 | 0 | 0 | 8.0 | 8.8 | 11.8 | 19.8 |
| 30° | 0 | 0 | 0 | 0 | 0 | 0 | 4.6 | 4.6 | 6.0 | 19.0 |
| 80° | 0 | 0 | 0 | 0 | 0 | 0 | 3.5 | 3.5 | 9.8 | 13.4 |
|_______________|___|____|____|___|____|____|______|______|______|______|
_______________________________________________________________________
| | | | |
| Concentration | | | |
| of lye (NaOH) | 25°B | 30°B | 35°B |
| | | | | | | | | |
| Duration of | | | | | | | | |
| action in | 10 | 30 | 1 | 10 | 30 | 1 | 10 | 30 |
| minutes | | | | | | | | |
| | | | | | | | | |
| Temperatures | Percentage shrinkages (Egyptian yarns) as under:-- |
| as under:-- | | | | | | | | |
| 2° | 19.8 | 21.5 | 22.7 | 22.7 | 22.7 | 24.2 | 24.5 | 24.7 |
| 18° | 20.1 | 21.0 | 21.2 | 22.0 | 22.3 | 23.5 | 23.8 | 24.7 |
| 30° | 19.5 | 19.0 | 18.5 | 19.5 | 19.8 | 20.7 | 21.0 | 21.1 |
| 80° | 13.7 | 14.2 | 15.0 | 15.1 | 15.5 | 15.0 | 15.2 | 15.4 |
|_______________|______|______|______|______|______|______|______|______|
The more important general indications of the above results are--(1) The
mercerisation action commences with a lye of 10°B., and increases with
increased strength of the lye up to a maximum at 35°B. There is,
however, a relatively slight increase of action with the increase of
caustic soda from 30-40°B. (2) For optimum action the temperature should
not exceed 15-20°C. (3) The duration of action is of proportionately
less influence as the concentration of the lye increases. As the maximum
effect is attained the action becomes practically instantaneous, the
only condition affecting it being that of penetration--i.e. actual
contact of cellulose and alkali.
(d) The question as to whether the process of 'mercerisation' involves
chemical as well as physical effects is briefly discussed. The author is
of opinion that, as the degree of lustre obtained varies with the
different varieties of cotton, the differentiation is occasioned by
differences in chemical constitution of these various cottons. The
influence of the chemical factors is also emphasised by the increased
dyeing capacity of the mercerised goods, which effect, moreover, is
independent of those conditions of strain or tension under mercerisation
which determine lustre. It is found in effect that with a varied range
of dye stuffs a given shade is produced with from 10 to 30 p.ct. less
colouring matter than is required for the ordinary, i.e. unmercerised,
goods.
In reference to the constants of strength and elasticity, Buntrock gives
the following results of observations upon a 40^{5} twofold yarn, five
threads of 50 cm. length being taken for each test(Prometheus, 1897, p.
690): (a) the original yarn broke under a load of 1440 grms.; (b)
after mercerisation without tension the load required was 2420 grms.;
(c) after mercerisation under strain, 1950 grms. Mercerisation,
therefore, increases the strength of the yarn from 30 to 66 p.ct., the
increase being lessened proportionately to the strain accompanying
mercerisation. _Elasticity_, as measured by the extension under the
breaking load, remains about the same in yarns mercerised under strain,
but when allowed to shrink under mercerisation there is an increase of
30-40 p.ct. over the original.
The _change of form_ sustained by the individual fibres has been studied
by H. Lange [Farberzeitung, 1898, 197-198], whose microphotographs of
the cotton fibres, both in length and cross-section, are reproduced. In
general terms, the change is from the flattened riband of the original
fibre to a cylindrical tube with much diminished and rounded central
canal. The effect of strain under mercerisation is chiefly seen in the
contour of the surface, which is smooth, and the obliteration at
intervals of the canal. Hence the increased transparency and more
complete reflection of the light from the surface, and the consequent
approximation to the optical properties of the silk fibre.
The work concludes with a section devoted to a description of the
various practical systems of mercerisation of yarns in general practice
in Germany, and an account of the methods adopted in dyeing the
mercerised yarns.
RESEARCHES ON MERCERISED COTTON.
A. FRAENKEL and P. FRIEDLAENDER (Mitt. k.-k. Techn. Gew. Mus., Wien,
1898, 326).
The authors, after investigation, are inclined to attribute the lustre
of mercerised cotton to the absence of the cuticle, which is destroyed
and removed in the process, partly by the chemical action of the alkali,
and partly by the stretching at one or other stage of the process. The
authors have investigated the action of alcoholic solutions of soda
also. The lustre effects are not obtained unless the action of water is
associated.
In conclusion, the authors give the following particulars of breaking
strains and elasticity:--
--------------------------------------------------------------------------
Treatment | Experiments | Breaking strain | Elasticity
--------------------------------------------------------------------------
| | | Elongation
| | Grammes | in mm.
| | |
Cotton unmercerised. | 1 | 360 | 20
| 2 | 356 | 20
| 3 | 360 | 22
| | |
Mercerised with | | |
Soda 35°B. | 1 | 530 | 44
| 2 | 570 | 40
| 3 | 559 | 35
| | |
Alcoholic soda 10 p.ct. | 1 | 645 | 24
cold | 2 | 600 | 27
| 3 | 610 | 33
| | |
Alcoholic soda 10 p.ct. | 5 | 740 | 33
hot | 2 | 730 | 38
| 3 | 690 | 30
--------------------------------------------------------------------------
FOOTNOTES:
[2] This and other similar references are to the matter of the original
volume (1895).
SECTION II. SYNTHETICAL DERIVATIVES--SULPHOCARBONATES AND ESTERS
(p. 25) ~Cellulose sulphocarbonate.~--Further investigations of the
reaction of formation as well as the various reactions of decomposition
of the compound, have not contributed any essential modification or
development of the subject as originally described in the author's first
communications. A large amount of experimental matter has been
accumulated in view of the ultimate contribution of the results to the
general theory of colloidal solutions. But viscose is a complex product
and essentially variable, through its pronounced tendency to progressive
decomposition with reversion of the cellulose to its insoluble and
uncombined condition. The solution for this reason does not lend itself
to exact measurement of its physical constants such as might elucidate
in some measure the progressive molecular aggregation of the cellulose
in assuming spontaneously the solid (hydrate) form. Reserving the
discussion of these points, therefore, we confine ourselves to recording
results which further elucidate special points.
_Normal and other celluloses._--We may certainly use the sulphocarbonate
reaction as a means of defining a normal cellulose. As already pointed
out, cotton cellulose passes quantitatively through the cycle of
treatments involved in solution as sulphocarbonate and decomposition of
the solution with regeneration as structureless or amorphous cellulose
(hydrate).
Analysis of this cellulose shows a fall of carbon percentage from 44.4
to 43.3, corresponding with a change in composition from
C_{6}H_{10}O_{5} to 4C_{6}H_{10}O_{5}.H_{2}O. The partial hydrolysis
affects the whole molecule, and is limited to this effect, whereas, in
the case of celluloses of other types, there is a fractionation of the
mass, a portion undergoing a further hydrolysis to compounds of lower
molecular weight and permanently soluble. Thus in the case of the wood
celluloses the percentage recovered from solution as viscose is from 93
to 95 p.ct. It is evident that these celluloses are not homogeneous. A
similar conclusion results from the presence of furfural-yielding
compounds with the observation that the hydrolysis to soluble
derivatives mainly affects these derivatives. In the empirical
characterisation of a normal cellulose, therefore, we may include the
property of quantitative regeneration or recovery from its solution as
sulphocarbonate.
In the use of the word 'normal' as applied to a 'bleached' cotton, we
have further to show in what respects the sulphocarbonate reaction
differentiates the bleached or purified cotton cellulose from the raw
product. The following experiments may be cited: Specimens of American
and Egyptian cottons in the raw state, freed from mechanical, i.e.
non-fibrous, impurities, were treated with a mercerising alkali, and the
alkali-cotton subsequently exposed to carbon disulphide. The product of
reaction was further treated as in the preparation of the ordinary
solution; but in place of the usual solution, structureless and
homogeneous, it was observed to retain a fibrous character, and the
fibres, though enormously swollen, were not broken down by continued
vigorous stirring. After large dilution the solutions were filtered, and
the fibres then formed a gelatinous mass on the filters. After
purification, the residue was dried and weighed. The American cotton
yielded 90.0 p.ct., and the Egyptian 92.0 p.ct. of its substance in the
form of this peculiar modification. The experiment was repeated,
allowing an interval of 24 hours to elapse between the conversion into
alkali-cotton and exposure of this to the carbon disulphide. The
quantitative results were identical.
There are many observations incidental to chemical treatments of cotton
fabrics which tend to show that the bleaching process produces other
effects than the mere removal of mechanical impurities. In the
sulphocarbonate reaction the raw cotton, in fact, behaves exactly as a
compound cellulose. Whether the constitutional difference between raw
and bleached cotton, thus emphasised, is due to the group of components
of the raw cotton, which are removed in the bleaching process, or to
internal constitutional changes determined by the bleaching treatments,
is a question which future investigation must decide.
_The normal sulphocarbonate (viscose)._--In the industrial applications
of viscose it is important to maintain a certain standard of composition
as of the essential physical properties of the solution, notably
viscosity. It may be noted first that, with the above-mentioned
exception, the various fibrous celluloses show but slight differences in
regard to all the essential features of the reactions involved. In the
mercerising reaction, or alkali-cellulose stage, it is true the
differences are considerable. With celluloses of the wood and straw
classes there is a considerable conversion into soluble
alkali-celluloses. If treated with water these are dissolved, and on
weighing back the cellulose, after thorough washing, treatment with
acid, and finally washing and drying, it will be found to have lost from
15 to 20 p.ct. in weight. The lower grade of celluloses thus dissolved
are only in part precipitated in acidifying the alkaline solution. On
the other hand, after conversion into viscose, the cellulose when
regenerated re-aggregates a large proportion of these lower grade
celluloses, and the final loss is as stated above, from 5 to 7 p.ct.
only.
Secondly, it is found that all the conditions obtaining in the
alkali-cellulose stage affect the subsequent viscose reaction and the
properties of the final solution. The most important are obviously the
proportion of alkali to cellulose and the length of time they are in
contact before being treated with carbon disulphide. An excess of
alkali beyond the 'normal' proportion--viz. 2NaOH per 1 mol.
C_{6}H_{10}O_{5}--has little influence upon the viscose reaction, but
lowers the viscosity of the solution of the sulphocarbonate prepared
from it. But this effect equally follows from addition of alkali to the
viscose itself. The alkali-cellulose changes with age; there is a
gradual alteration of the molecular structure of the cellulose, of which
the properties of the viscose when prepared are the best indication.
There is a progressive loss of viscosity of the solution, and a
corresponding deterioration in the structural properties of the
cellulose when regenerated from it--especially marked in the film form.
In regard to viscosity the following observations are typical:--
(a) A viscose of 1.8 p.ct. cellulose prepared from an
alkali-cellulose (cotton) fourteen days old.
(b) Viscose of 1.8 p.ct. cellulose from an alkali-cellulose
(cotton) three days old.
(c) Glycerin diluted with 1/3 vol. water.
a b b c
Diluted with
equal vol.
water
Times of flow of equal volumes from 112 321 103 170
narrow orifice in seconds
Similarly the cellulose in reverting to the solid form from these
'degraded' solutions presents a proportionate loss of cohesion and
aggregating power expressed by the inferior strength and elasticity of
the products. Hence, in the practical applications of the product where
the latter properties are of first importance, it is necessary to adopt
normal standards, such as above indicated, and to carefully regulate all
the conditions of treatment in each of the two main stages of reaction,
so that a product of any desired character may be invariably obtained.
Incidentally to these investigations a number of observations have been
made on the alkali-cellulose (cotton) after prolonged storage in closed
vessels. It is well known that starch undergoes hydrolysis in contact
with aqueous alkalis of a similar character to that determined by acids
[Béchamp, Annalen, 100, 365]. The recent researches of Lobry de Bruyn
[Rec. Trav. Chim. 14, 156] upon the action of alkaline hydrates in
aqueous solution on the hexoses have established the important fact of
the resulting mobility of the CO group, and the interchangeable
relationships of typical aldoses and ketoses. It was, therefore, not
improbable that profound hydrolytic changes should occur in the
cellulose molecule when kept for prolonged periods as alkali-cellulose.
We may cite an extreme case. A series of products were examined after
12-18 months' storage. They were found to contain only 3-5 p.ct.
'soluble carbohydrates'; these were precipitated by Fehling's solution
but without reduction on boiling. They were, therefore, of the cellulose
type. On acidifying with sulphuric acid and distilling, traces only of
volatile acid were produced. It is clear, therefore, that the change of
molecular weight of the cellulose, the disaggregation of the undoubtedly
large molecule of the original 'normal' cellulose--which effects are
immediately recognised in the viscose reactions of such products--are of
such otherwise limited character that they do not affect the
constitution of the unit groups. We should also conclude that the
cellulose type of constitution covers a very wide range of minor
variations of molecular weight or aggregation.
The resistance of the normal cellulose to the action of alkalis under
these hydrolysing conditions should be mentioned in conjunction with the
observations of Lange, and the results of the later investigations of
Tollens, on its resistance to 'fusion' with alkaline hydrates at high
temperatures (180°). The degree of resistance has been established only
on the empirical basis of weighing the product recovered from such
treatment. The product must be investigated by conversion into typical
cellulose derivatives before we can pronounce upon the constitutional
changes which certainly occur in the process. But for the purpose of
this discussion it is sufficient to emphasise the extraordinary
resistance of the normal cellulose to the action of alkalis, and to
another of the more significant points of differentiation from starch.
_Chemical constants of cellulose sulphocarbonate (solution)._--In
investigations of the solutions we make use of various analytical
methods, which may be briefly described, noting any results bearing upon
special points.
_Total alkali._--This constant is determined by titration in the usual
way. The cellulose ratio, C_{6}H_{10}O_{5} : 2NaOH, is within the
ordinary error of observation, 2 : 1 by weight. A determination of alkali
therefore determines the percentage of cellulose.
_Cellulose_ may be regenerated in various ways--viz. by the action of
heat, of acids, of various oxidising compounds. It is purified for
weighing by boiling in neutral sulphite of soda (2 p.ct. solution) to
remove sulphur, and in very dilute acids (0.33 p.ct. HCl) to decompose
residues of 'organic' sulphur compounds. It may also be treated with
dilute oxidants. After weighing it may be ignited to determine residual
inorganic compounds.
_Sulphur._--It has been proved by Lindemann and Motten [Bull. Acad. R.
Belg. (3), 23, 827] that the sulphur of sulphocarbonates (as well as of
sulphocyanides) is fully oxidised (to SO_{3}) by the hypochlorites
(solutions at ordinary temperatures). The method may be adapted as
required for any form of the products or by-products of the viscose
reaction to be analysed for _total sulphur_.
The sulphur present in the form of dithiocarbonates, including the
typical cellulose xanthogenic acid, is approximately isolated and
determined as CS_{2} by adding a zinc salt in excess, and distilling off
the carbon disulphide from a water bath. From freshly prepared solutions
a large proportion of the disulphide originally interacting with the
alkali and cellulose is recovered, the result establishing the general
conformity of the reaction to that typical of the alcohols. On keeping
the solutions there is a progressive interaction of the bisulphide and
alkali, with formation of trithiocarbonates and various sulphides. In
decomposing these products by acid reagents hydrogen sulphide and free
sulphur are formed, the estimation of which presents no special
difficulties.
In the spontaneous decomposition of the solution a large proportion of
the sulphur resumes the form of the volatile disulphide. This is
approximately measured by the loss in total sulphur in the following
series of determinations, in which a viscose of 8.5 p.ct. strength
(cellulose) was dried down as a thin film upon glass plates, and
afterwards analysed:
(a) Proportion of sulphur to cellulose (100 pts.) in original.
(b) After spontaneous drying at ordinary temperature.
(c) After drying at 40°C.
(d) As in (c), followed, by 2 hours' heating at 98°.
(e) As in (c), followed by 5 hours' heating at 98°.
a b c d e
Total sulphur 40.0 25.0 31.0 23.7 10.4
The dried product in (b) and (c) was entirely resoluble in water; in
(d) and (e), on the other hand, the cellulose was fully regenerated,
and obtained as a transparent film.
_Iodine reaction._--Fresh solutions of the sulphocarbonate show a fairly
constant reaction with normal iodine solution. At the first point, where
the excess of iodine visibly persists, there is complete precipitation
of the cellulose as the bixanthic sulphide; and this occurs when the
proportion of iodine added reaches 3I_{2} : 4Na_{2}O, calculated to the
total alkali.
_Other decompositions._--The most interesting is the interaction which
occurs between the cellulose xanthogenate and salts of ammonia, which is
taken advantage of by C. H. Stearn in his patent process of spinning
artificial threads from viscose. The insoluble product which is formed
in excess of the solution of ammonia salt is free from soda, and
contains 9-10 p.ct. total sulphur. The product retains its solubility in
water for a short period. The solution may be regarded as containing the
ammonium cellulose xanthate. This rapidly decomposes with liberation of
ammonia and carbon disulphide, and separation of cellulose (hydrate). As
precipitated by ammonium-chloride solution the gelatinous thread
contains 15 p.ct. of cellulose, with a sp.gr. 1.1. The process of
'fixing'--i.e. decomposing the xanthic residue--consists in a short
exposure to the boiling saline solution. The further dehydration, with
increase of gravity and cellulose content, is not considerable. The
thread in its final air-dry state has a sp.gr. 1.48.
* * * * *
~Cellulose Benzoates.~--These derivatives have been further studied by the
authors. The conditions for the formation of the monobenzoate
[C_{6}H_{9}O_{4}.O.CO.Ph] are very similar to those required for the
sulphocarbonate reaction. The fibrous cellulose (cotton), treated with a
10 p.ct. solution NaOH, and subsequently with benzoyl chloride, gives
about 50 p.ct. of the theoretical yield of monobenzoate. Converted by 20
p.ct. solution NaOH into alkali-cellulose, and with molecular
proportions as below, the following yields were obtained:--
Calc. for
Monobenzoate
(a) C_{6}H_{10}O_{5} : 2.0-2.5 NaOH : C_{6}H_{5}.COCl-- 150.8}
}164.0
(b) C_{6}H_{10}O_{5} : 2.0-2.5 NaOH : 1.5 mol. C_{6}H_{5}COCl 159.0}
An examination of (a) showed that some dibenzoate (about 7 p.ct.) had
been formed. The product () was exhaustively treated with cuprammonium
solution, to which it yielded about 20 p.ct. of its weight, which was
therefore unattacked cellulose.
Under conditions as above, but with 2.5 mol. C_{6}H_{5}COCl, a careful
comparison was made of the behaviour of the three varieties of cotton,
which were taken in the unspun condition and previously fully bleached
and purified.
___________________________________________________________________
| | | | |
| | Sea Island | Egyptian | American |
|________________________________|____________|__________|__________|
| | | | |
| Aggregate yield of benzoate | 153 | 148 | 152 |
| Moisture in air dry state | 5.28 | 5.35 | 5.15 |
| Proportion of dibenzoate p.ct. | 8.30 | 13.70 | 9.4 |
| Yield of cellulose by | 58.0 | 54.0 | 58.3 |
| saponification | | | |
|________________________________|____________|__________|__________|
It appears from these results that the benzoate reaction may proceed to
a higher limit (dibenzoate) in the case of Egyptian cotton. This would
necessarily imply a higher limit of 'mercerisation,' under equal
conditions of treatment with the alkaline hydrate. It must be noted that
in the conversion of the fibrous cellulose into these (still) fibrous
monobenzoates, there are certain mechanical conditions imported by the
structural features of the ultimate fibres. For the elimination of the
influence of this factor a large number of quantitative comparisons will
be necessary. The above results are therefore only cited as typical of a
method of comparative investigation, more especially of the still open
questions of the cause of the superior effects in mercerisation of
certain cottons (see p. 23). It is quite probable that chemical as well
as structural factors co-operate in further differentiating the cottons.
Further investigation of the influence upon the benzoate reaction, of
increase of concentration of the soda lye, used in the preliminary
alkali cellulose reaction, from 20 to 33 p.ct. NaOH, established (1)
that there is no corresponding increase in the benzoylation, and (2)
that this ester reaction and the sulphocarbonate reaction are closely
parallel, in that the degree and limit of reaction are predetermined by
the conditions of formation of the alkali cellulose.
_Monobenzoate_ prepared as above described is resistant to all solvents
of cellulose and of the cellulose esters, and is therefore freed from
cellulose by treatment with the former, and from the higher benzoate by
treatment with the latter. Several of these, notably pyridine, phenol
and nitrobenzene, cause considerable swelling and gelatinisation of the
fibres, but without solution.
_Structureless celluloses_ of the 'normal' type, and insoluble therefore
in alkaline lye, treated under similar conditions to those described
above for the fibrous celluloses, yield a higher proportion of
dibenzoate. The following determinations were made with the cellulose
(hydrate) regenerated from the sulphocarbonate:--
Mol. proportions of reagents Yield Dibenzoate p.ct.
C_{6}H_{10}O_{5} : 2NaOH : 2BzCl 145 34.7
[Caustic soda at 10 per cent. NaOH]
C_{6}H_{10}O_{5} : 4NaOH : 2BzCl 162 62.7
[Caustic soda at 20 per cent. NaOH]
_Limit of reaction._--The cellulose in this form having shown itself
more reactive, it was taken as the basis for determining the maximum
proportion of OH groups yielding to this later reaction. The systematic
investigations of Skraup [Monatsh. 10, 389] have determined that as
regards the interacting groups the molecular proportions 1 OH : 7 NaOH :
5 BzCl, ensure complete or maximum esterification. The maximum of OH
groups in cellulose being 4, the reagents were taken in the proportion
C_{6}H_{10}O_{5} : 4 [7 NaOH : 5 BzCl]. The yield of crude product, after
purifying as far as possible from the excess of benzoic acid, was 240
p.ct. [calculated for dibenzoate 227 p.ct.]. On further investigating
the crude product by treatment with solvents, it was found to have still
retained benzoic acid. There was also present a proportion of only
partially attacked cellulose (monobenzoate). The soluble benzoate
amounted to 90 p.ct. of the product. It may be generally concluded that
the dibenzoate represents the normal maximum but that with the hydrated
and partly hydrolysed cellulose molecule, as obtained by regeneration
from the sulphocarbonate, other OH groups may react, but they are only a
fractional proportion in relation to the unit group C_{6}H_{10}O_{5}. In
this respect again there is a close parallelism between the
sulphocarbonate and benzoyl-ester reactions.
_The dibenzoate_, even when prepared from the fibrous celluloses, is
devoid of structure, and its presence in admixture with the fibrous
monobenzoate is at once recognised as it constitutes a structureless
incrustation. Under the microscope its presence in however minute
proportion is readily observed. As stated it is soluble in certain of
the ordinary solvents of the cellulose esters, e.g. chloroform, acetic
acid, nitrobenzene, pyridine, and phenol. It is not soluble in ether or
alcohol.
_Hygroscopic moisture of benzoates._--The crude monobenzoate retains
5.0-5.5 p.ct. moisture in the air-dry condition. After removal of the
residual cellulose this is reduced to 3.3 p.ct. under ordinary
atmospheric conditions. The purified dibenzoates retain 1.6 p.ct. under
similar conditions.
_Analysis of benzoates._--On saponification of these esters with
alcoholic sodium hydrate, anomalous results are obtained. The acid
numbers, determined by titration in the usual way, are 10-20 p.ct. in
excess of the theoretical, the difference increasing with the time of
boiling. Similarly the residual cellulose shows a deficiency of 5-9
p.ct.
It is by no means improbable that in the original ester reaction there
is a constitutional change in the cellulose molecule causing it to break
down in part under the hydrolysing treatment with formation of acid
products. This point is under investigation. Normal results as regards
acid numbers, on the other hand, are obtained by saponification with
sodium ethylate in the cold, the product being digested with the
half-saturated solution for 12 hours in a closed flask.
The following results with specimens of mono- and dibenzoate, purified,
as far as possible, may be cited:
Combustion results Saponification results
Calc. C_{6}H_{5}.COOH Calc. Cellulose Calc.
Monobenzoate C 56.60 58.65}
H 5.06 5.26} 46.0 45.9 58.0 60.8
Dibenzoate C 63.10 64.86}
H 3.40 4.86} 65.5 66.6 34.3 40.3
The divergence of the numbers, especially for the dibenzoate, in the
case of the hydrogen, and yield of cellulose on hydrolysis are
noteworthy. They confirm the probability of the occurrence of secondary
changes in the ester reactions.
_Action of nitrating acid upon the benzoates._--From the benzoates above
described, mixed nitro-nitric esters are obtained by the action of the
mixture of nitric and sulphuric acids. The residual OH groups of the
cellulose are esterified and substitution by an NO_{2} group takes place
in the aromatic residue, giving a mixed nitric nitrobenzoic ester. The
analysis of the products points to the entrance of 1 NO_{2} group in the
benzoyl residue in either case; in the cellulose residue 1 OH readily
reacts. Higher degrees of nitration are attained by the process of
solution in concentrated nitric acid and precipitation by pouring into
sulphuric acid. In describing these mixed esters we shall find it
necessary to adopt the C_{12} unit formula.
In analysing these products we have employed the Dumas method for _total
nitrogen_. For the O.NO_{2} groups we have found the nitrometer and the
Schloesing methods to give concordant results. For the NO_{2} groups it
was thought that Limpricht's method, based upon reduction with stannous
chloride in acid solution (HCl), would be available. The quantitative
results, however, were only approximate, owing to the difficulty of
confining the reduction to the NO_{2} groups of the nitrobenzoyl
residue. By reduction with ammonium sulphide the O.NO_{2} groups were
entirely removed as in the case of the cellulose nitrates; the NO_{2}
was reduced to NH_{2} and there resulted a cellulose amidobenzoate,
which was diazotised and combined with amines and phenols to form yellow
and red colouring matters, the reacting residue remaining more or less
firmly combined with the cellulose.
_Cellulose dinitrate-dinitrobenzoate, and cellulose
trinitrate-dinitrobenzoate._--On treating the fibrous benzoate--which is
a dibenzoate on the C_{12} basis--with the acid mixture under the usual
conditions, a yellowish product is obtained, with a yield of 140-142
p.ct. The nitrobenzoate is insoluble in ether alcohol, but is soluble in
acetone, acetic acid, and nitrobenzene. In purifying the product the
former solvent is used to remove any cellulose nitrates. To obtain the
maximum combination with nitroxy-groups, the product was dissolved in
concentrated nitric acid, and the solution poured into sulphuric acid.
The following analytical results were obtained (a) for the product
obtained directly from the fibrous benzoate and purified as indicated,
(b) for the product from the further treatment of (a) as described:
Found Calc. for
(a) (b) Dinitrate Trinitrate
dinitrobenzoate dinitrobenzoate
Total Nitrogen 7.84 8.97 7.99 9.24
O.NO_{2} " 5.00 5.45 4.00 5.54
NO_{2} (Aromatic) 2.84 3.52 3.99 3.70
With the two benzoyl groups converted into nitro-benzoyl in each
product, the limit of the ester reaction with the cellulose residue is
reached at the third OH group.
The nitrogen in the amidobenzoate resulting from the reduction with
ammonium sulphide was 4.5 p.ct.--as against 5.0 p.ct. calculated. The
moisture retained by the fibrous nitrate--nitrobenzoate--in the air-dry
state was found to be 1.97 p.ct.
The product from the structureless dibenzoate or tetrabenzoate on the
C_{12} formula, was prepared and analysed with the following results:
Calc. for
Mononitrate tetranitrobenzoate
Total Nitrogen 6.76 7.25
O.NO_{2} " 1.30 1.45
NO_{2} " (Aromatic) 5.46 5.80
The results were confirmed by the yield of product, viz. 131 p.ct. as
against the calculated 136 p.ct. They afford further evidence of the
generally low limit of esterification of the cellulose molecule. From
the formation of a 'normal' tetracetate--i.e. octacetate of the C_{12}
unit--we conclude that 4/5 of the oxygen atoms are hydroxyl oxygen. Of
the 8 OH groups five only react in the mixed esters described above, and
six only in the case of the simple nitric esters. The ester reactions
are probably not simple, but accompanied by secondary reactions within
the cellulose molecule.
* * * * *
(p. 34) ~Cellulose Acetates.~--In the first edition (p. 35) we have
committed ourselves to the statement that 'on boiling cotton with acetic
anhydride and sodium acetate no reaction occurs.' This is erroneous. The
error arises, however, from the somewhat vague statements of
Schutzenberger's researches which are current in the text-books [e.g.
Beilstein, 1 ed. p. 586] together with the statement that reaction only
occurs at elevated temperatures (180°). As a matter of fact, reaction
takes place at the boiling temperature of the anhydride. We have
obtained the following results with bleached cotton:
Yield Calc. for Monoacetate
C_{6}H_{7}O_{4}O.C_{2}H_{3}O
Ester reaction 121 p.ct. 125 p.ct.
{Cellulose 79.9 79.9
Saponification {
{Acetic acid 29.9 29.4
This product is formed without apparent structural alteration of the
fibre. It is entirely insoluble in all the ordinary solvents of the
higher acetates. Moreover, it entirely resists the actions of the
special solvents of cellulose--e.g. zinc chloride and cuprammonium. The
compound is in other respects equally stable and inert. The hygroscopic
moisture under ordinary atmospheric conditions is 3.2 p.ct.
_Tetracetate._--This product is now made on the manufacturing scale: it
has yet to establish its industrial value.
NITRIRUNG VON KOHLENHYDRATEN.
W. WILL und P. LENZE (Berl. Ber., 1898, 68).
~NITRATES OF CARBOHYDRATES.~
(p. 38) The authors have studied the nitric esters of a typical series
of the now well-defined carbohydrates--pentoses, hexoses, both aldoses
and ketoses--bioses and trioses, the nitrates being prepared under
conditions designed to produce the highest degree of esterification.
Starch, wood, gum, and cellulose were also included in the
investigations. The products were analysed and their physical properties
determined. They were more especially investigated in regard to
temperatures of decomposition, which were found to lie considerably
lower than that of the cellulose nitrates. They also show marked and
variable instability at 50° C. A main purpose of the inquiry was to
throw light upon a probable cause of the instability of the cellulose
nitrates, viz. the presence of nitrates of hydrolysed products or
carbohydrates of lower molecular weight.
The most important results are these:
_Monoses._--The _aldoses_ are fully esterified, in the pentoses 4 OH, in
the hexoses 5 OH groups reacting. The pentose nitrates are comparatively
stable at 50°; the hexose nitrates on the other hand are extremely
unstable, showing a loss of weight of 30-40 p.ct. when kept 24 hours at
this temperature.
Xylose is differentiated by tending to pass into an anhydride form
(C_{5}H_{10}O_{5}-H_{2}O) under this esterification. When treated in
fact with the mixed acids, instead of by the process usually adopted by
the authors of solution in nitric acid and subsequent addition of the
sulphuric acid, it is converted into the dinitrate
C_{5}H_{6}O_{2}.(NO_{3})_{2}.
_Ketoses_ (C_{6}).--These are sharply differentiated from the corresponding
aldoses by giving _tri_nitrates C_{6}H_{7}O_{2}(NO_{3})_{3} instead
of _penta_nitrates, the remaining OH groups probably undergoing internal
condensation. The products are, moreover, _extremely stable_. It is also
noteworthy that levulose gave this same product, the trinitrate of the
anhydride (levulosan) by both methods of nitration (_supra_).
_The bisaccharides or bioses_ all give the octonitrates. The degree of
instability is variable. Cane-sugar gives a very unstable nitrate. The
lactose nitrate is more stable. Thus at 50° it loses only 0.7 p.ct. in
weight in eight days; at 75° it loses 1 p.ct. in twenty-four hours, but
with a rapid increase to 23 p.ct. in fifty-four hours. The maltose
octonitrate melts (with decomposition) at a relatively high temperature,
163°-164°. At 50°-75° it behaves much like the lactose nitrate.
_Trisaccharide._--Raffinose yielded the product
C_{18}H_{21}O_{5}.(NO_{3})_{11}.
_Starch_ yields the hexanitrate (C_{12}) by both methods of nitration.
The product has a high melting and decomposing point, viz. 184°, and
when thoroughly purified is quite stable. It is noted that a yield of
157 p.ct. of this nitrate was obtained, and under identical conditions
cellulose yielded 170 p.ct.
_Wood gum_, from beech wood, gave a tetranitrate (C_{10} formula)
insoluble in all the usual solvents for this group of esters.
The authors point out in conclusion that the conditions of instability
and decomposition of the nitrates of the monose-triose series are
exactly those noted with the cellulose nitrates as directly prepared and
freed from residues of the nitrating acids. They also lay stress upon
the superior stability of the nitrates of the anhydrides, especially of
the ketoses.
NITRATED CARBOHYDRATES AS FOOD MATERIAL FOR MOULDS.
THOMAS BOKORNY (Chem. Zeit., 1896, 20, 985-986).
(p. 38) Cellulose trinitrate (nitrocellulose) will serve as a food
supply for moulds when suspended in distilled water containing the
requisite mineral matter and placed in the dark. The growth is rapid,
and a considerable quantity of the vegetable growth accumulates round
the masses of cellulose nitrate, but no growth is observed if mineral
matter is absent. Cellulose itself cannot act as a food supply, and it
seems probable that if glycerol is present cellulose nitrate is no
longer made use of.
NITRATION OF CELLULOSE, HYDROCELLULOSE, AND OXYCELLULOSE.
LEO VIGNON (Compt. rend., 1898, 126, 1658-1661).
(p. 38) Repeated treatment of cellulose, hydrocellulose, and
oxycellulose with a mixture of sulphuric and nitric acids in large
excess, together with successive analyses of the compounds produced,
showed that the final product of the reaction corresponded, in each
case, with the fixation of 11 NO groups by a molecule containing 24
atoms of carbon. On exposure to air, nitrohydrocellulose becomes yellow
and decomposes; nitro-oxycellulose is rather more stable, whilst
nitrocellulose is unaffected. The behaviour of these nitro-derivatives
with Schiff's reagent, Fehling's solution, and potash show that all
three possess aldehydic characters, which are most marked in the case of
nitro-oxycellulose. The latter also, when distilled with hydrochloric
acid, yields a larger proportion of furfuraldehyde than is obtained from
nitrocellulose and nitrohydrocellulose.
* * * * *
~CELLULOSE NITRATES-EXPLOSIVES.~
(p. 38) The uses of the cellulose nitrates as a basis for explosives are
limited by their fibrous character. The conversion of these products
into the structureless homogeneous solid or semi-solid form has the
effect of controlling their combustion. The use of nitroglycerin as an
agent for this purpose gives the curious result of the admixture of two
high or blasting explosives to produce a new explosive capable of
extended use for military purposes. The leading representatives of this
class of propulsive explosives, or 'smokeless powders' are ballistite
and cordite, the technology of which will be found fully discussed in
special manuals of the subject. Since the contribution of these
inventions to the development of cellulose chemistry does not go beyond
the broad, general facts above mentioned, we must refer the reader for
technical details to the manuals in question.
There are, however, other means of arriving at structureless cellulose
nitrates. One of these has been recently disclosed, and as the results
involve chemical and technical points of novelty, which are dealt with
in a scientific communication, we reproduce the paper in question,
viz.:--
A RE-INVESTIGATION OF THE CELLULOSE NITRATES.
A. LUCK and C. F. CROSS (J. Soc. Chem. Ind., 1900).
The starting-point of these investigations was a study of the nitrates
obtained from the structureless cellulose obtained from the
sulphocarbonate (viscose). This cellulose in the form of a fine meal was
treated under identical conditions with a sample of pure cotton
cellulose, viz. digested for 24 hours in an acid mixture containing in
100 parts HNO_{3}--24 : H_{2}SO_{4}--70 : H_{2}O--6: the proportion of
acid to cellulose being 60 : 1--. After careful purification the
products were analysed with the following results:
Soluble in
Nitrogen Ether alcohol
Fibrous nitrate 13.31 4.3 p.ct.
Structureless nitrate 13.35 5.6 "
Examined by the 'heat test' (at 80°) and the 'stability test' (at 135°)
they exhibited the usual instability, and in equal degrees. Nor were the
tests affected by exhaustive treatment with ether, benzene, and alcohol.
From this it appears that the process of solution as sulphocarbonate and
regeneration of the cellulose, though it eliminates certain constituents
of an ordinary bleached cellulose, which might be expected to cause
instability, has really no effect in this direction. It also appears
that instability may be due to by-products of the esterification process
derived from the cellulose itself.
The investigation was then extended to liquids having a direct solvent
action on these higher nitrates, more especially acetone. It was
necessary, however, to avoid this solvent action proper, and having
observed that dilution with water in increasing proportions produced a
graduated succession of physical changes in the fibrous ester, we
carried out a series of treatments with such diluted acetones.
Quantities of the sample (A), purified as described, but still unstable,
were treated each with five successive changes of the particular liquid,
afterwards carefully freed from the acetone and dried at 40°C. The
products, which were found to be more or less disintegrated, were then
tested by the ordinary heat test, stability test, and explosion test,
with the results shown in the table on next page.
In this series of trials the sample 'A' was used in the condition of
pulp, viz. as reduced by the process of wet-beating in a Hollander. A
similar series was carried out with the guncotton in the condition in
which it was directly obtained from the ester reaction. The results were
similar to above, fully confirming the progressive character of the
stabilisation with increasing proportions of acetone. These results
prove that washing with the diluted acetone not only rendered the
nitrate perfectly stable, but that the product was more stable than that
obtained by the ordinary process of purification, viz. long-continued
boiling and washing in water. We shall revert to this point after
briefly dealing with the associated phenomenon of structural
disintegration. This begins to be well marked when the proportion of
acetone exceeds 80 p.ct. The optimum effect is obtained with mixtures of
90 to 93 acetone and 10 to 7 water (by volume). In a slightly diluted
acetone of such composition, the guncotton is instantly attacked, the
action being quite different from the gelatinisation which precedes
solution in the undiluted solvent. The fibrous character disappears, and
the product assumes the form of a free, bulky, still opaque mass, which
rapidly sinks to the bottom of the containing vessel. The disintegration
of the bulk of the nitrate is associated with
__________________________________________________________________________
| | | | | |
| | Proportions by volume | | | |
| |________________________| Temperature | Heat | Heat |
| | | | of | Test | Test |
| | Acetone | Water | Explosion | 80° | 134° |
|___________________|______________|_________|_____________|_______|_______|
| | | | | | |
| __| | | Deg. | Mins. | Mins. |
| | 20 | 80 | 137 | 3 | 4 |
| | 30 | 70 | 160 | 3 | 4 |
| | 40 | 60 | 180 | 7 | 18 |
| | | | | | No |
| | | | | | fumes |
| | | | | | after |
| From 'A' sample. | 50 | 50 | 187.5 | 55 | 100 |
| | 60 | 40 | 187 | 45 | 100 |
| | 70 | 30 | 185 | 45 | 100 |
| | 80 | 20 | | 50 | 100 |
| __| 92 | 8 | 185 | 50 | 100 |
| | Structure- | | | | |
| | less powder. | | | | |
| " 'B' sample __| 50 | 50 | 183 | 35 | 100 |
| " 'C' sample | Ordinary service | 185 | 10 | 41 |
| | guncotton | | | |
|___________________|______________|_________|_____________|_______|_______|
a certain solvent action, and on adding an equal bulk of water, the
dissolved nitrate for the most part is precipitated, at the same time
that the undissolved but disintegrated and swollen product undergoes
further changes in the direction of increase of hardness and density.
The product being now collected on a filter, freed from acetone by
washing with water and dried, is a hard and dense powder the fineness of
which varies according to the attendant conditions of treatment. With
the main product in certain cases there is found associated a small
proportion of nitrate retaining a fibrous character, which may be
separated by means of a fine sieve. On examining such a residue, we
found it to contain only 5.6 p.ct. N, and as it was insoluble in strong
acetone, it may be regarded as a low nitrate or a mixture of such with
unaltered cellulose. Confirming this we found that the product passing
through the sieve showed an increase of nitrogen to 13.43 p.ct. from the
13.31 p.ct. in the original. Tested by the heat test (50 minutes) and
stability test (no fumes after 100 minutes), we found the products to
have the characteristics previously noticed.
It is clear, therefore, that this specifically regulated action of
acetone produces the effects (a) of disintegration, and (b)
stabilisation. It remains to determine whether the latter effect was
due, as might be supposed, to the actual elimination of a compound or
group of compounds present in the original nitrate, and to be regarded
as the effective cause of instability. It is to be noted first that as a
result of the treatment with the diluted acetone and further dilution
after the specific action is completed, collecting the disintegrated
product on a filter and washing with water, the loss of weight sustained
amounts to 3 to 4 p.ct. This loss is due, therefore, to products
remaining dissolved in the filtrate--that is to say, in the much diluted
acetone. These filtrates are in fact opalescent from the presence of a
portion of nitrate in a colloidal (hydrated) form. On distilling off the
acetone, a precipitation is determined. The precipitates are nitrates of
variable composition, analysis showing from 9 to 12 p.ct. of nitric
nitrogen. The filtrate from these precipitates containing only
fractional residues of acetone still shows opalescence. On
long-continued boiling a further precipitation is determined, the
filtrates from which are clear. It was in this final clear filtrate that
the product assumed to cause the instability of the original nitrate
would be present. The quantity, however, is relatively so small that we
have only been able to obtain and examine it as residue from evaporation
to dryness. An exhaustive qualitative examination established a number
of negative characteristics, with the conclusion that the products were
not direct derivatives of carbohydrates nor aromatic compounds. On the
other hand the following positive points resulted. Although the original
diluted acetone extract was neutral to test papers, yet the residue was
acid in character. It contained combined nitric groups, fused below 200°
giving off acid vapours, and afterwards burning with a smoky flame. On
adding lead acetate to the original clear solution, a well-marked
precipitation was determined. The lead compounds thus isolated are
characteristic. They have been obtained in various ways and analysed.
The composition varies with the character of the solution in which the
lead compound is formed. Thus in the opalescent or milky solutions in
which a proportion of cellulose nitrate is held in solution or
semi-solution by the acetone still present, the lead acetate causes a
dense coagulation. The precipitates dried and analysed showed 16-20
p.ct. PbO and 11-9 p.ct. N. It is clear that the cellulose nitrates are
associated in these precipitates with the lead salts of the acid
compounds in question. When the latter are obtained from clear
solutions, i.e. in absence of cellulose nitrates, they contain 60-63
p.ct. PbO and 3.5 p.ct. N (obtained as NO).
In further confirmation of the conclusion from these results, viz. that
the nitrocelluloses with no tendency to combine with PbO are associated
with acid products or by-products of the ester reaction combining with
the oxide, the lead reagent was allowed to react in the presence of 90
p.ct. acetone. Water was added, the disintegrated mass collected, washed
with dilute acetic acid, and finally with water. Various estimations of
the PbO fixed in this way have given numbers varying from 2 to 2.5 p.ct.
Such products are perfectly stable. This particular effect of
stabilisation appears, therefore, to depend upon the combination of
certain acid products present in ordinary nitrocelluloses with metallic
oxides. In order to further verify this conclusion, standard specimens
of cellulose nitrates have been treated with a large number of metallic
salts under varying conditions of action. It has been finally
established (1) that the effects in question are more particularly
determined by treatment with salts of lead and zinc, and (2) that the
simplest method of treatment is that of boiling the cellulose nitrates
with dilute aqueous solutions of salts of these metals, preferably the
acetates. The following results may be cited, obtained by boiling a
purified 'service' guncotton (sample C) with a 1 p.ct. solution of lead
acetate and of zinc acetate respectively. After boiling 60 minutes the
nitrates were washed free from the soluble metallic salts, dried and
tested.
__________________________________________________
| | | |
| | Heat Test | Heat Test |
| | at 80° | at 134° |
|__________________________|___________|___________|
| | | |
| Original sample C | 10 | 41 |
|Treated with lead acetate | 67 | 45 |
| " zinc " | 91 | 45 |
|__________________________|___________|___________|
In conclusion we may briefly resume the main points arrived at in these
investigations.
_Causes of instability of cellulose nitrates._--The results of our
experiments so far as to the causes of instability in cellulose nitrates
may be summed up as follows:--
(1) Traces of free nitrating acids, which can only occur in the finished
products through careless manufacture, will undoubtedly cause
instability, indicated strongly by the ordinary heat test at 80°, and to
a less extent by the heat test at 134°.
(2) Other compounds exist in more intimate association with the
cellulose nitrates causing instability which cannot be removed by
exhaustive washing with either hot or cold water, by digestion in cold
dilute alkaline solutions such as sodium carbonate, or by extracting
with ether, alcohol, benzene, &c.; these compounds, however, are soluble
in the solvents of highly nitrated cellulose such as acetone, acetic
ether, pyridine, &c., even when these liquids are so diluted with water
or other non-solvent liquids to such an extent that they have little or
no solvent action upon the cellulose nitrate itself. These solutions
containing the bodies causing instability are neutral to test paper, but
become acid upon evaporation by heating. (This probably explains the
presence of free acid when guncotton is purified by long-continued
boiling in water without any neutralising agent being present.)
(3) The bodies causing instability are products or by-products of the
original ester reaction, acid bodies containing nitroxy-groups, but
otherwise of ill-defined characteristics. They combine with the oxides
of zinc or lead, giving insoluble compounds. They are precipitated from
their solutions in diluted acetone upon the addition of soluble salts of
these metals.
(4) Cellulose nitrates are rendered stable either by eliminating these
compounds, or by combining them with the oxides of lead or zinc whilst
still in association with cellulose nitrates.
(5) Even the most perfectly purified nitrocellulose will slowly
decompose with formation of unstable acid products by boiling for a long
time in water. This effect is much more apparent at higher temperatures.
_Dense structureless or non-fibrous cellulose nitrates_ can be
industrially prepared (1) by nitrating the amorphous forms of cellulose
obtained from its solution as sulphocarbonate (viscose). The cellulose
in this condition reacts with the closest similarity to the original
fibrous cellulose; the products are similar in composition and
properties, including that of instability.
(2) By treating the fibrous cellulose nitrates with liquid solvents of
the high nitrate diluted with non-solvent liquids, and more especially
water. The optimum effect is a specific disintegration or breaking down
of their fibrous structure quite distinct from the gelatinisation which
precedes solution in the undiluted solvent, and occurring within narrow
limits of variation in the proportion of the diluting and non-solvent
liquid--for industrial work the most convenient solution to employ is
acetone diluted with about 10 p.ct. of water by volume.
The industrial applications of these results are the basis of English
patents 5286 (1898), 18,868 (1898), 18,233 (1898), Luck and Cross (this
Journal, 1899, 400, 787).
The structureless guncotton prepared as above described is of quite
exceptional character, and entirely distinct from the ordinary fibrous
nitrate or the nitrate prepared by precipitation from actual solution in
an undiluted solvent.[3] By the process described, the nitrate is
obtained at a low cost in the form of a very fine, dense, structureless,
white powder of great purity and stability, entirely free from all
mechanical impurities. The elimination of these mechanical impurities,
and also to a very great extent of coloured compounds contained in the
fibrous nitrate, makes the product also useful in the manufacture of
celluloids, artificial silk, &c., whilst its very dense form gives it a
great advantage over ordinary fibrous guncotton for use in shells and
torpedoes, and for the manufacture of gelatinised gunpowders, &c. It can
be compressed with ease into hard masses; and experiments are in
progress with a view of producing from it, in admixture with 'retaining'
ingredients, a military explosive manufactured by means of ordinary
black gunpowder machinery and processes.
_Manufacture of sporting powder._--The fact that the fibrous structure
of ordinary guncotton or other cellulose nitrate can be completely or
partially destroyed by treatment with diluted acetone and without
attendant solution, constitutes a process of value for the manufacture
of sporting powder having a base of cellulose nitrate of any degree of
nitration. The following is a description of the hardening process.
'Soft grains' are manufactured from ordinary guncotton or other
cellulose nitrate either wholly or in combination with other
ingredients, the process employed being the usual one of revolving in a
drum in the damp state and sifting out the grains of suitable size after
drying. These grains are then treated with diluted acetone, the degree
of dilution being fixed according to the hardness and bulk of the
finished grain it is desired to produce (J. Soc. Chem. Ind., 1899, 787).
Owing to the wide limits of dilution and corresponding effect, the
process allows of the production of either a 'bulk' or a 'condensed'
powder.
We prefer to use about five litres of the liquid to each one kilo. of
grain operated upon, as this quantity allows of the grains being freely
suspended in the liquid upon stirring. The grains are run into the
liquid, which is then preferably heated to the boiling-point for a few
minutes whilst the whole is gently stirred. Under this treatment the
grains assume a more or less rounded gelatinous condition according to
the strength of the liquid. There is, however, no solution of the
guncotton and practically no tendency of the grains to cohere. Each
grain, however, is acted upon _throughout_ and perfectly _equally_.
After a few minutes' treatment, water is gradually added, when the
grains rapidly harden. They are then freed from acetone and certain
impurities by washing with water, heating, and drying. The process is of
course carried out in a vessel provided with any means for gentle
stirring and heating, and with an outlet for carrying off the
volatilised solvent which is entirely recovered by condensation, the
grains parting with the acetone with ease.
_Stabilising cellulose nitrates._--The process is of especial value in
rendering stable and inert the traces of unstable compounds which always
remain in cellulose nitrate after the ordinary boiling and washing
process. It is of greatest value in the manufacture of collodion cotton
used for the preparation of gelatinous blasting explosives and all
explosives composed of nitroglycerin and cellulose nitrates. Such
mixtures seem peculiarly liable to decomposition if the cellulose
nitrate is not of exceptional stability (J. Soc. Chem. Ind., 1899,
787).
EMPLOI DE LA CELLULOSE POUR LA FABRICATION DE FILS BRILLANTS IMITANT LA
SOIE.
E. BRONNERT (1) (Rev. Mat. Col., 1900, September, 267).
V. ~USE OF CELLULOSE IN THE MANUFACTURE OF IMITATIONS OF SILK
(LUSTRA-CELLULOSE).~
(p. 45) _Introduction._--The problem of spinning a continuous thread of
cellulose has received in later years several solutions. Mechanically
all resolve themselves into the preparation of a structureless filtered
solution of cellulose or a cellulose derivative, and forcing through
capillary orifices into some medium which either absorbs or decomposes
the solvent. The author notes here that the fineness and to a great
extent the softness of the product depends upon the dimensions of the
capillary orifice and concentration of the solution. The technical idea
involved in the spinning of artificial fibres is an old one. Réaumur (2)
forecast its possibility, Audemars of Lausanne took a patent as early as
1855 (3) for transforming nitrocellulose into fine filaments which he
called 'artificial silk.' The idea took practical shape only when it
came to be used in connection with filaments for incandescent lamps. In
this connection we may mention the names of the patentees:--Swinburne
(4), Crookes, Weston (5), Swan (6), and Wynne and Powell (7). These
inventors prepared the way for Chardonnet's work, which has been
followed since 1888 with continually increasing success.
At this date the lustra-celluloses known may be divided into four
classes.
1. 'Artificial silks' obtained from the nitrocelluloses.
2. 'Lustra-cellulose' made from the solution of cellulose in
cuprammonium.
3. 'Lustra-cellulose' prepared from the solution of cellulose in
chloride of zinc.
4. 'Viscose silks,' by the decomposition of sulphocarbonate of cellulose
(Cross and Bevan).
GROUP 1. The early history of the Chardonnet process is discussed and
some incidental causes of the earlier failures are dealt with. The
process having been described in detail in so many publications the
reader is referred to these for details. [See Bibliography, (1) and (2),
(3) and (4).] The denitrating treatment was introduced in the period
1888-90 and of course altogether changed the prospects of the industry;
not only does it remove the high inflammability, but adds considerably
to softness, lustre, and general textile quality. In Table I will be
found some important constants for the nitrocellulose fibre; also the
fibre after denitration and the comparative constants for natural silk.
TABLE 1.
_______________________________________________________________________
| | | |
| | Tenacity | Elasticity |
| | (grammes) | (% elongation) |
|__________________________________________|___________|________________|
| | | |
| Nitrocellulose according to Chardonnet | | |
| German Patent No. 81,599 | 150 | 23 |
| The same after denitration | 110 | 8 |
| Denitrated fibre moistened with water | 25 | -- |
| Nitrocellulose: Bronnert's German Patent | | |
| No. 93,009 | 125 | 28 |
| The same after denitration (dry) | 115 | 13 |
| The same after denitration (wetted) | 32 | -- |
| Natural silk | 300 | 18 |
|__________________________________________|___________|________________|
1. Tenacity is the weight in grammes required to break the
thread.
2. Elasticity is the elongation per cent. at breaking.
The numbers are taken for thread of 100 deniers (450 metres of
0.05 grammes = 1 denier). It must be noted that according to
the concentration of the solution and variations in the process
of denitration the constants for the yarn are subject to very
considerable variation.
In regard to the manufacture a number of very serious difficulties have
been surmounted. First, instead of drying the nitrated cellulose, which
often led to fires, &c., it was found better to take it moist from the
centrifugal machine, in which condition it is dissolved (5). It was
next found that with the concentrated collodion the thread could be spun
direct into the air, and the use of water as a precipitant was thus
avoided.
With regard to denitration which is both a delicate and disagreeable
operation: none of the agents recommended to substitute the sulphydrates
have proved available. Of these the author mentions ferrous chloride
(6), ferrous chloride in alcohol (7), formaldehyde (8),
sulphocarbonates. The different sulphydrates (9) have very different
effects. The calcium compound tends to harden and weaken the thread. The
ammonia compound requires great care and is costly. The magnesium
compound works rapidly and gives the strongest thread. Investigations
have established the following point. In practice it is not necessary to
combine the saponification of cellulose ester with complete reduction of
the nitric acid split off. The latter requires eight molecules of
hydrogen sulphide per one molecule tetranitrocellulose, but with
precautions four molecules suffice. It is well known that the
denitration is nearly complete, traces only of nitric groups surviving.
Their reactions with diphenylamine allow a certain identification of
artificial silks of this class. Various other inventors, e.g. Du Vivier
(10), Cadoret (11), Lehner (12), have attempted the addition of other
substances to modify the thread. These have all failed. Lehner, who
persisted in his investigations, and with success, only attained this
success, however, by leaving out all such extraneous matters. Lehner
works with 10 p.ct. solutions; Chardonnet has continually aimed at
higher concentration up to 20 p.ct. Lehner has been able very much to
reduce his pressures of ejection in consequence; Chardonnet has had to
increase up to pressures of 60 k. per cm. and higher. The latter
involves very costly distributing apparatus. Lehner made next
considerable advance by the discovery of the fact that the addition of
sulphuric acid to the collodion caused increase of fluidity (13), which
Lehner attributes to molecular change. Chardonnet found similar results
from the addition of aldehyde and other reagents (14), but not such as
to be employed for the more concentrated collodions. The author next
refers to his discoveries (15) that alcoholic solutions of a number of
substances, organic and inorganic, freely dissolve the lower cellulose
nitrates. The most satisfactory of these substances is chloride of
calcium (16). It is noted that acetate of ammonia causes rapid changes
in the solution, which appear to be due to a species of hydrolysis. The
result is sufficiently remarkable to call for further investigation. The
chloride of calcium, it is thought possible, produces a direct
combination of the alcohol with a reactive group of the nitrocellulose.
The fluidity of this solution using one mol. CaCl_{2} per 1 mol.
tetranitrate (17) reaches a maximum in half an hour's heating at
60°-70°C. The fluidity is increased by starting from a cotton which has
been previously mercerised. After nitration there is no objection to a
chlorine bleach. Chardonnet has found on the other hand that in
bleaching before nitration there is a loss of spinning quality in the
collodion. The author considers that the new collodion can be used
entirely in place of the ordinary ether-alcohol collodion. With regard
to the properties of the denitrated products they fix all basic colours
without mordant and may be regarded as oxycellulose therefore. The
density of the thread is from 1.5 to 1.55. The thread of 100 deniers
shows a mean breaking strain of 120 grammes with an elasticity of 8-12
p.ct. The cardinal defect of these fibres is their property of
combination with water. Many attempts have been made to confer
water-resistance (18), but without success. Strehlenert has proposed the
addition of formaldehyde (19), but this is without result (20). In
reference to these effects of hydration, the author has made
observations on cotton thread, of which the following table represents
the numerical results:
Breaking Strain
Mean of 20 experiments
Skein of bleached cotton without treatment 825
Skein of bleached cotton without treatment, but wetted 942
Ditto after conversion into hexanitrate, dry 884
The above, wetted 828
The cotton denitrated from above, dry 529
The cotton denitrated as above and wetted 206
The author considers that other patents which have been taken for
spinning nitrocellulose are of little practical account (21) and (22).
The same conclusion also applies to the process of _Langhans_, who
proposes to spin solutions of cellulose in sulphuric acid (23) (24) and
mixtures of sulphuric acid and phosphoric acid.
GROUP 2. _Lustra-cellulose._--Thread prepared by spinning solutions of
cellulose in cuprammonium.
This product is made by the Vereinigte Glanzstoff-Fabriken, Aachen,
according to a series of patents under the names of H. Pauly, M. Fremery
and Urban, Consortium mulhousien pour la fabrication de fils brillants,
E. Bronnert, and E. Bronnert and Fremery and Urban (1). The first patent
in this direction was taken by Despeissis in 1890 (2). It appears this
inventor died shortly after taking the patent (3) The matter was later
developed by Pauly (4) especially in overcoming the difficulty of
preparing a solution of sufficient concentration. (It is to be noted
that Pauly's patents rest upon a very slender foundation, being
anticipated in every essential detail by the previous patent of
Despeissis.) For this very great care is required, especially, first,
the condition of low temperature, and, secondly, a regulated proportion
of copper and ammonia to cellulose. The solution takes place more
rapidly if the cellulose has been previously oxidised. Such cellulose
gives an 8 p.ct. solution, and the thread obtained has the character of
an oxycellulose, specially seen in its dyeing properties. The best
results are obtained, it appears, by the preliminary mercerising
treatment and placing the alkali cellulose in contact with copper and
ammonia. (All reagents employed in molecular proportions.) The author
notes that the so-called hydrocellulose (Girard) (5) is almost insoluble
in cuprammonium, as is starch. It is rendered soluble by alkali
treatment.
GROUP 3. _Lustra-cellulose_ prepared by spinning a solution of cellulose
in concentrated chloride of zinc.
This solution has been known for a long time and used for making
filaments for incandescent lamps. The cellulose threads, however, have
very little tenacity. This is no doubt due to the conditions necessary
for forming the solution, the prolonged digestion causing powerful
hydrolysis (1). Neither the process of Wynne and Powell (2) nor that of
Dreaper and Tompkins (3), who have endeavoured to bring the matter to a
practical issue, are calculated to produce a thread taking a place as a
textile. The author has described in his American patent (4) a method of
effecting the solution in the cold, viz. again by first mercerising the
cellulose and washing away the caustic soda. This product dissolves in
the cold and the solution remains unaltered if kept at low temperature.
Experiments are being continued with these modifications of the process,
and the author anticipates successful results. The modifications having
the effect of maintaining the high molecular weight of the cellulose, it
would appear that these investigations confirm the theory of Cross and
Bevan that the tenacity of a film or thread of structureless regenerated
cellulose is directly proportional to the molecular weight of the
cellulose, i.e. to its degree of molecular aggregation (5).
GROUP 4. 'Viscose' silks obtained by spinning solutions of xanthate of
cellulose.
In 1892, Cross and Bevan patented the preparation of a new and curious
compound of cellulose, the thiocarbonate (1) (2) (3). Great hopes were
based upon this product at the time of its discovery. It was expected
to yield a considerable industrial and financial profit and also to
contribute to the scientific study of cellulose. The later patents of C.
H. Stearn (4) describe the application of viscose to the spinning of
artificial silk. The viscose is projected into solutions of chloride of
ammonium and washed in a succession of saline solutions to remove the
residual sulphur impurities. The author remarks that though it has a
certain interest to have succeeded in making a thread from this compound
and thus adding another to the processes existing for this purpose, he
is not of opinion that it shows any advance on the lustra-cellulose (2)
and (3). He also considers that the bisulphide of carbon, which must be
regarded as a noxious compound, is a serious bar to the industrial use
of the process, and for economic work he considers that the regeneration
of ammonia from the precipitating liquors is necessary and would be as
objectionable as the denitration baths in the collodion process. The
final product not being on the market he does not pronounce a finally
unfavourable opinion.
The author and the Vereinigte Glanzstoff-Fabriken after long
investigation have decided to make nothing but the lustra-cellulose (2)
and (3). A new factory at Niedermorschweiler, near Mulhouse, is
projected for this last production.
BIBLIOGRAPHY
_Introduction_
(1) Bull. de la Soc. industr. de Mulhouse, 1900.
(2) Réaumur, Mémoire pour servir à l'histoire des insectes, 1874, 1, p.
154.
(3) English Pat. No. 283, Feb. 6, 1855.
(4) Swinburne, Electrician, 18, 28, 1887, p. 256.
(5) Weston (Swinburne), Electrician, 18, 1887, p. 287. Eng. Pat. No.
22866, Sept. 12, 1882.
(6) German Pat. No. 3029. English Pat. No. 161780, April 28, 1884
(Swan).
(7) Wynne-Powell, English Pat. No. 16805, Dec. 22, 1884.
_Group I_
(1) German Pat No. 38368, Dec. 20, 1885. German Pat. No. 46125, March 4,
1888. German Pat. No. 56331, Feb. 6, 1890. German Pat. No. 81599, Oct.
11, 1893. German Pat. No. 56655, April 23, 1890. French Pat. No. 231230,
June 30, 1893.
(2) Industrie textile, 1899, 1892. Wyss-Noef, Zeitschrift für angewandte
Chemie, 1899, 30, 33. La Nature, Jan. 1, 1898, No. 1283. Revue générale
des sciences, June 30, 1898.
(3) German Pat. No. 46125, March 4, 1888. German Pat. No. 56655, April
23, 1890.
(4) Swan, English Pat. 161780, June 28, 1884. See also Béchamp, Dict. de
Chimie de Wurtz.
(5) German Pat. No. 81599, Oct 11, 1893.
(6) Béchamp, art. Cellulose, Dict. de Chimie de Wurtz, p. 781.
(7) Chardonnet, addit. March 3, 1897, to the French Pat. 231230, May 30,
1893.
(8) Knofler, French Pat. 247855, June 1, 1895. German Pat. 88556, March
28, 1894.
(9) Béchamp, art. Cellulose, Dict. de Chimie de Wurtz. Blondeau, Ann.
Chim. et Phys. (3), 1863, 68, p. 462.
(10) Revue industrielle, 1890, p. 194. German Pat. 52977, March 7, 1889.
(11) French Pat. 256854, June 2, 1896.
(12) German Pat. 55949, Nov. 9, 1889. German Pat. 58508, Sept. 16, 1890.
German Pat. 82555, Nov. 15, 1894.
(13) German Pat. 58508, Sept. 16, 1900.
(14) French Pat. 231230, June 30, 1893.
(15) German Pat. 93009, Nov. 19, 1895. French Pat. 254703, March 12,
1896. English Pat. 6858, March 28, 1896.
(16) American Pat. 573132, Dec. 15, 1896.
(17) This proportion is the most advantageous, and furnishes the best
liquid collodions that can be spun.
(18) French Pat. 259422, Sept. 3, 1896.
(19) English Pat. 22540, 1896.
(20) Application for German Pat. not granted, 4933 IV. 296, Mar. 16,
1897.
(21) German Pat. 96208, Feb. 10, 1897. Addit. Pat. 101844 and 102573,
Dec. 10, 1897.
(22) Oberle et Newbold, French Pat. 25828, July 22, 1896. Granquist,
Engl. applic. 2379, Nov. 28, 1899.
(23) German Pat. 72572, June 17, 1891.
(24) Voy. Stern, Ber., 28, ch. 462.
_Group II_
(1) German Pat. 98642, Dec. 1, 1897 (Pauly). French Pat. 286692, March
10, 1899, and addition of October 14, 1899 (Fremery and Urban). French
Pat. 286726, March 11, 1899, and addition of December 4, 1899. German
Pat. 111313, March 16, 1899 (Fremery and Urban). English Pat. 18884,
Sept. 19, 1899 (Bronnert). English Pat. 13331, June 27, 1899 (Consort.
mulhousien).
(2) French Pat. 203741, Feb. 12, 1890.
(3) The actual lapse of this patent is due to the death of Despeissis
shortly after it was taken.
(4) Without questioning the good faith of Pauly, it is nevertheless a
fact that the original patent remains as a document, and therefore that
the value of the Pauly patents is very questionable.
(5) Girard, Ann. Chim. et Phys, 1881 (5), 24, p. 337-384.
_Group III_
(1) Cross and Bevan, Cellulose, 1895, p. 8.
(2) English Pat. 16805, Dec. 22, 1884.
(3) English Pat. 17901, July 30, 1897.
(4) Bronnert, American Pat. 646799, April 3, 1900.
(5) Cross and Bevan, Cellulose, 1895, p. 12.
_Group IV_
(1) English Pat. 8700, 1892. German Pat. 70999, Jan. 13, 1893.
(2) English Pat. 4713, 1896. German Pat. 92590, Nov. 21, 1896.
(3) Comptes rendus (loc. cit.). Berichte, c. 9, 65a.
(4) English Pat. 1020, 1898. German Pat. 108511, Oct. 18, 1898.
~Artificial Silk--Lustra-cellulose.~
C. F. CROSS and E. J. BEVAN (J. Soc. Chem. Ind., 1896, 317).
The object of this paper is mainly to correct current statements as to
the artificial or 'cellulose silks' being explosive or highly
inflammable (ibid., 1895, 720). A specimen of the 'Lehner' silk was
found to retain only 0.19 p.ct. total nitrogen, showing that the
denitration is sufficiently complete to dispose of any suggestion of
high inflammability.
The product yielded traces only of furfural; on boiling with a 1 p.ct.
solution of sodium hydrate, the loss of weight was 9.14 p.ct.; but the
solution had no reducing action on Fehling's solution. The product in
denitration had therefore reverted completely to a cellulose (hydrate),
no oxy-derivative being present.
* * * * *
The authors enter a protest against the term 'artificial silk' as
applied to these products, and suggest 'lustra-cellulose.'
DIE KÜNSTLICHE SEIDE-IHRE HERSTELLUNG, EIGENSCHAFTEN UND VERWENDUNG.
CARL SÜVERN, Berlin, 1900, J. Springer.
~ARTIFICIAL SILK--ITS PRODUCTION, PROPERTIES, AND APPLICATIONS.~
This work of some 130 pages is an important monograph on the subject of
the preparation of artificial cellulose threads--so far as the technical
elements of the problems involved are discussed and disclosed in the
patent literature. The first section, in fact, consists almost
exclusively of the several patent specifications in chronological order
and ranged under the sub-sections: (a) The Spinning of Nitrocellulose
(collodion); (b) The Spinning of other Solutions of Cellulose; (c)
The Spinning of Solutions of the Nitrogenous Colloids.
In the second section the author deals with the physical and chemical
proportions of the artificial threads.
_Chardonnet 'silk'_ is stated to have a mean diameter of 35µ, but with
considerable variations from the mean in the individual fibres; equally
wide variations in form are observed in cross-section. The general form
is elliptical, but the surface is marked by deep striæ, and the
cross-section is therefore of irregular outline. This is due to
irregular conditions of evaporation of the solvents, the thread being
'spun' into the air from cylindrical orifices of regulated dimensions.
Chardonnet states that when the collodion is spun into alcohol the
resultant thread is a perfect cylinder (Compt. rend. 1889, 108, 962).
The strength of the fibre is variously stated at from 50-80 p.ct. that
of 'boiled off' China tram; the true elasticity is 4-5 p.ct., the
elongation under the breaking strain 15-17 p.ct. The sp.gr. is 1.49,
i.e. 3-5 p.ct. in excess of boiled off silk.
_Lehner 'silk'_ exhibits the closest similarity to the Chardonnet
product. In cross-section it is seen to be more regular in outline, and
a round, pseudo-tubular form prevails, due to the conditions of
shrinkage and collapse of the fibre in parting with the solvents, and in
then dehydrating. The constants for 'breaking strain,' both in the
original and moistened condition, for elasticity, &c., are closely
approximate to those for the Chardonnet product.
_Pauly 'silk'._--The form of the ultimate fibres is much more regular
and the contour of the cross-section is smooth. The product shows more
resistance to moisture and to alkaline solutions.
_Viscose 'silk'_ is referred to in terms of a communication appearing in
'Papier-Zeitung,' 1898, 2416.
In the above section the following publications are referred
to: Chardonnet, 'Compt. rend.,' 1887, 105, 900; and 1889, 108,
962; Silbermann, 'Die Seide,' 1897, v. 2, 143; Herzog,
'Farber-Zeitung,' 1894/5, 49-50; Thiele, ibid. 1897, 133; O.
Schlesinger, 'Papier-Zeitung,' 1895, 1578-81, 1610-12.
_Action of Reagents upon Natural and Artificial Silks._
1. _Potassium hydrate_ in solution of maximum concentration dissolves
the silks proper, (a) China silk on slight warming, (b) Tussah silk
on boiling. The cellulose 'silks' show swelling with discolouration, but
the fibrous character is not destroyed even on boiling.
2. _Potassium hydrate_ 40 p.ct. China silk dissolves completely at
65°-85°; Tussah silk swells considerably at 75° and dissolves at
100°-120°. The cellulose 'silks' are attacked with discolouration; at
140° (boiling-point of the solution) there is progressive solvent
action, but the action is incomplete. The Pauly product is most
resistant.
3. _Zinc chloride_, 40 p.ct. solution. Both the natural silks and
lustra-celluloses are attacked at 100°, and on raising the temperature
the further actions are as follows: China silk is completely dissolved
at 110-120°; Tussah silk at 130-135°; the collodion products at
140-145°; the Pauly product was again most resistant, dissolving at
180°.
4. _Alkaline cupric oxide_ (glycerin) solution was prepared by
dissolving 10 grs. of the sulphate in 100 c.c. water, adding 5 grs.
glycerin and 10 c.c. of 40 p.ct. KOH. In this solution the China silk
dissolved at the ordinary temperature; Tussah silk and the
lustra-celluloses were not appreciably affected.
5. _Cuprammonium solution_ was prepared by dissolving the precipitated
cupric hydrate in 24 p.ct. ammonia. In this reagent also the China silk
dissolved, and the Tussah silk as well as the lustra-celluloses
underwent no appreciable change.
6. _An ammoniacal solution of nickel oxide_ was prepared by dissolving
the precipitated hydrated oxide in concentrated ammonia. The China silk
was dissolved by this reagent; Tussah silk and the lustra-celluloses
entirely resisted its action.
7. _Fehling's solution_ is a solvent of the natural silks, but is
without action on the lustra-celluloses.
8. _Chromic acid_--20 p.ct. CrO_{3}--solution dissolves both the natural
silks and the lustra-celluloses at the boiling temperature of the
solution.
9. _Millon's reagent_, at the boiling solution, colours the natural
silks violet: the lustra-celluloses give no reaction.
10. _Concentrated nitric acid_ attacks the natural silks powerfully in
the cold; the lustra-celluloses dissolve on heating.
11. _Iodine solution_ (I in KI) colours the China silk a deep brown,
Tussah a pale brown; the celluloses from collodion are coloured at first
brown, then blue. The Pauly product, on the other hand, does not react.
12. _Diphenylamine sulphate._--A solution of the base in concentrated
sulphuric acid colours the natural silks a brown; the collodion 'silks'
give a strong blue reaction due to the presence of residual
nitro-groups. The Pauly product is not affected.
13. _Brucin sulphate_ in presence of concentrated sulphuric acid colours
the natural silks only slightly (brown); the collodion 'silks' give a
strong red colouration. The Pauly product again is without reaction.
14. _Water._--The natural silks do not soften in the mouth as do the
lustra-celluloses.
15. _Water of condition_ was determined by drying at 100°; the following
percentages resulted (a). The percentages of water (b) taken up from
the atmosphere after forty-three hours' exposure were:
(a) (b)
China (raw) silk 7.97 2.24
Tussah silk 8.26 5.00
Lustra-celluloses:
Chardonnet (Besançon) 10.37 5.64
" Spreitenbach 11.17 5.77
Lehner 10.71 5.97
Pauly 10.04 6.94
16. _Behaviour on heating at 200°._--After two hours' heating at this
temperature the following changes were noted:
China silk Much discoloured (brown).
Tussah silk Scarcely affected.
Lustra-celluloses:
Chardonnet Converted into a blue-black charcoal, retaining the
Lehner form ofthe fibres.
Pauly A bright yellow-brown colouration, without carbonisation.
17. The _losses of weight_ accompanying these changes and calculated per
100 parts of fibre dried at 100° were:
China silk 3.18
Tussah silk 2.95
Lustra-celluloses:
Chardonnet 33.70
Lehner 26.56
Pauly 1.61
18. _Inorganic constituents._--Determinations of the total ash gave for
the first five of the above, numbers varying from 1.0 to 1.7 p.ct. The
only noteworthy point in the comparison was the exceptionally small ash
of the Pauly product, viz. 0.096 p.ct.
19. _Total nitrogen._--The natural silks contain the 16-17 p.ct. N
characteristic of the proteids. The lustra-celluloses contain 0.05-0.15
p.ct. N which in those spun from collodion is present in the form of
nitric groups.
The points of chemical differentiation which are established by the
above scheme of comparative investigation are summed up in tabular form.
_Methods of dyeing._--The lustra-celluloses are briefly discussed. The
specific relationship of these forms of cellulose to the colouring
matters are in the main those of cotton, but they manifest in the
dye-bath the somewhat intensified attraction which characterises
mercerised cotton, or more generally the cellulose hydrates.
_Industrial applications_ of the lustra-celluloses are briefly noticed
in the concluding section of the book.
FOOTNOTES:
[3] With these products it is easy to observe that they have a definite
fusion point 5°-10° below the temperature of explosion.
SECTION III. DECOMPOSITIONS OF CELLULOSE SUCH AS THROW LIGHT ON THE
PROBLEM OF ITS CONSTITUTION
UEBER CELLULOSE.
G. BUMCKE und R. WOLFFENSTEIN (Berl. Ber., 1899, 2493).
(p. 54) _Theoretical Preface._--The purpose of these investigations is
the closer characterisation of the products known as 'oxycellulose' and
'hydracellulose,' which are empirical aggregates obtained by various
processes of oxidation and hydrolysis; these processes act concurrently
in the production of the oxycelluloses. The action of hydrogen peroxide
was specially investigated. An oxycellulose resulted possessing strongly
marked aldehydic characteristics. The authors commit themselves to an
explanation of this paradoxical result, i.e. the production of a body
of strongly 'reducing' properties by the action of an oxidising agent
upon the inert cellulose molecule (? aggregate) as due to the
_hydrolytic_ action of the peroxide: following Wurster (Ber. 22, 145),
who similarly explained the production of reducing sugars from cane
sugar by the action of the peroxide.
The product in question is accordingly termed _hydralcellulose_. By the
action of alkalis this is resolved into two bodies of alcoholic
(cellulose) and acid ('acid cellulose') characteristics respectively.
The latter in drying passes into a lactone. The acid product is also
obtained from cellulose by the action of alkaline lye (boiling 30 p.ct.
NaOH) and by solution in Schweizer's reagent.
It is considered probable that the cellulose nitrates are hydrocellulose
derivatives, and experimental evidence in favour of this conclusion is
supplied by the results of 'nitrating' the celluloses and their oxy- and
hydro- derivatives. Identical products were obtained.
_Experimental investigations._--The filter paper employed as 'original
cellulose,' giving the following numbers on analysis:
C 44.56 44.29 44.53 44.56
H 6.39 6.31 6.46 6.42
was exposed to the action of pure distilled H_{2}O_{2} at 4-60 p.ct.
strength, at ordinary temperatures until disintegrated: a result
requiring from nineteen to thirty days. The series of products gave the
following analytical results:
C 43.61 43.61 43.46 43.89 44.0 43.87 43.92 43.81
H 6.00 6.29 6.28 6.26 6.13 6.27 6.24 6.27
results lying between the requirements of the formulæ:
5 C_{6}H_{10}O_{5}.H_{2}O and 8 C_{6}H_{10}O_{5}.H_{2}O.
Hydrazones were obtained with 1.7-1.8 p.ct. N. Treated with caustic soda
solution the hydrazones were dissolved in part: on reprecipitation a
hydrazone of unaltered composition was obtained. The original product
shows therefore a uniform distribution of the reactive CO- groups.
The hydralcellulose boiled with Fehling's solution reduced 1/12 of the
amount required for an equal weight of glucose.
Digested with caustic soda solution it yielded 33 p.ct. of its weight of
the soluble 'acid cellulose.' This product was purified and analysed
with the following result: C 43.35 H 6.5. For the direct production of
the 'acid' derivative, cellulose was boiled with successive quantities
of 30 p.ct. NaOH until _dissolved_. It required eight treatments of one
hour's duration. On adding sulphuric acid to the solutions the product
was precipitated. Yield 40 p.ct. Analyses:
C 43.8 43.8 43.7
H 6.2 6.2 6.3
The cellulose reprecipitated from solution in Schweizer's reagent gave
similar analytical results:
C 43.9 43.8 44.0
H 6.5 6.3 6.4
_Conversion into nitrates._--The original cellulose, hydral- and acid
cellulose were each treated with 10 times their weight of HNO_{3} of
1.48 sp.gr. and heated at 85° until the solution lost its initial
viscosity.
The products were precipitated by water and purified by solution in
acetone from which two fractions were recovered, the one being
relatively insoluble in ethyl alcohol. The various nitrates from the
several original products proved to be of almost identical composition,
C 32.0 H 4.2 N 8.8
with a molecular weight approximately 1350. The conclusion is that
these products are all derivatives of a 'hydralcellulose'
6C_{6}H_{10}O_{5}H_{2}O.
FORMATION OF FURFURALDEHYDE FROM CELLULOSE, OXYCELLULOSE, AND
HYDROCELLULOSE.
By LEO VIGNON (Compt. rend., 1898, 126, 1355-1358).
(p. 54) Hydrocellulose, oxycellulose, and 'reduced' cellulose, the last
named being apparently identical with hydrocellulose, were obtained by
heating carefully purified cotton wool (10 grams) in water (1,000 c.c.),
with (1) 65 c.c. of hydrochloric acid (1.2 sp.gr.), (2) 65 c.c. of
hydrochloric acid and 80 grams of potassium chlorate, (3) 65 c.c. of
hydrochloric acid and 50 grams of stannous chloride. From these and some
other substances, the following percentage yields of furfuraldehyde were
obtained: Hydrocellulose, 0.854; oxycellulose, 2.113; reduced cellulose,
0.860; starch, 0.800; bleached cotton, 1.800; oxycellulose, prepared by
means of chromic acid, 3.500. Two specimens of oxycellulose were
prepared by treating cotton wool with hydrochloric acid and potassium
chlorate (A), and with sulphuric acid and potassium dichromate (B), and
25 grams of each product digested with aqueous potash. Of the product A,
16.20 grams were insoluble in potash, 2.45 grams were precipitated on
neutralisation of the alkaline solution, and 6.35 grams remained in
solution, whilst B yielded 11.16 grams of insoluble matter, 1.42 grams
were precipitated by acid, and 12.42 grams remained in solution. The
percentage yields of furfuraldehyde obtained from these fractions were
as follows: A, insoluble, 0.86; precipitated, 4.35; dissolved, 1.10. B,
insoluble, 0.76; precipitated, 5.11; dissolved, 1.54. It appears, from
the foregoing results, that the cellulose molecule, after oxidation, is
easily decomposed by potash, the insoluble and larger portion having all
the characters of the original cellulose, whilst the soluble portion is
of an aldehydic nature, and contains a substance, precipitable by acids,
which yields a relatively large amount of furfuraldehyde.
UNTERSUCHUNGEN ÜBER DIE OXYCELLULOSE.
O. V. FABER und B. TOLLENS (Berl. Ber., 1899, 2589).
~Investigations of Oxycellulose.~
(p. 61) The author's results are tersely summed up in the following
conclusions set forth at the end of the paper: The oxycelluloses are
mixtures of cellulose and a derivative oxidised compound which contains
one more atom O than cellulose (cellulose = C_{6}H_{10}O_{5}), and for
which the special designation _Celloxin_ is proposed.
Celloxin may be formulated C_{8}H_{6}O_{6} or C_{6}H_{10}O_{6}, of which
the former is the more probable.
The various oxycelluloses may be regarded as containing one celloxin
group to 1-4 cellulose groups, according to the nature of the original
cellulose, and the degree of oxidation to which subjected. These groups
are in chemical union.
Celloxin has not been isolated. On boiling the oxycelluloses with
lime-milk it is converted into isosaccharinic and dioxybutyric acids.
The insoluble residue from the treatment is cellulose.
The following oxycelluloses were investigated:
A. _Product of action of nitric acid upon pine wood_ (Lindsey and
Tollens, Ann. 267, 366).--The oxycelluloses contained
1 mol celloxin: {2 mol. cellulose on 6 hours' heating
{3 mol. cellulose on 3 hours' heating
with a ratio H : O = 1 : 9 and 1 : 8.7 respectively: they yielded 7
p.ct. furfural.
B. _By action of bromine in presence of water and_ CaCO_{3} _upon
cotton_.--Yield, (air-dry) 85 p.ct. Empirical composition
C_{12}H_{20}O_{11} = C_{6}H_{10}O_{5}.C_{6}H_{10}O_{6}: yielded furfural
1.7 p.ct.
C. _Cotton and nitric acid at_ 100°, two and a half hours (Cross and
Bevan).--Yield, 70 p.ct. Composition
4 C_{6}H_{10}O_{5}.C_{6}H_{8}O_{6}
yielded furfural 2.3 p.ct.
D. _Cotton and nitric acid at_ 100° (four hours).--A more highly
oxidised product resulted, viz. 3 C_{6}H_{10}O_{5}.C_{6}H_{8}O_{6}:
yielded furfural 3.2 p.ct.
_By-products of oxidation._--The liquors from B were found to contain
saccharic acid: the acid from C and B contained a dibasic acid which
appeared to be tartaric acid.
The isolation of (1) isosaccharinic and (2) dioxybutyric acid from the
products of digestion of the oxycelluloses with lime-milk at 100° was
effected by the separation of their respective calcium salts, (1) by
direct crystallisation, (2) by precipitation alcohol after separation of
the former.
CELLULOSES, HYDRO- AND OXYCELLULOSES, AND CELLULOSE ESTERS.
L. VIGNON (Bull. Soc. Chim., 1901 [3], 25, 130).
(a) _Oxycelluloses from cotton, hemp, flax, and ramie._--The
comparative oxidation of these celluloses, by treatment with HClO_{3}
at 100°, gave remarkably uniform results, as shown by the following
numbers, showing extreme variations: yields, 68-70 p.ct.; hydrazine
reaction, N fixed 1.58-1.69; fixation of basic colouring matters
(relative numbers), saffranine, 100-200, methylene blue, 100-106. The
only points of difference noted were (1) hemp is somewhat more resistant
to the acid oxidation; (2) the cotton oxycellulose shows a somewhat
higher (25 p.ct.) cupric reduction.
(b) _'Saccharification' of cellulose, cellulose hydrates, and
hydrocellulose._--The products were digested with dilute hydrochloric
acid six hours at 100°, and the cupric reduction of the soluble products
determined and calculated to dextrose.
100 grms. of gave reducing products equal to Dextrose
Purified cotton 3.29
" Hydrocellulose 9.70
Cotton mercerised (NaOH 30° B.) 4.39
Cotton mercerised (NaOH 40° B.) 3.51
Cellulose reprecipitated from cuprammonium 4.39
Oxycellulose 14.70
Starch 98.6
These numbers show that cellulose may be hydrated both by mercerisation
and solution, without affecting the constitutional relationships of the
CO groups. The results also differentiate the cellulose series from
starch in regard to hydrolysis.
(c) _Cellulose and oxycellulose nitrates._--The nitric esters of
cellulose have a strong reducting action on alkaline copper solutions.
The author has studied this reaction quantitatively for the esters both
of cellulose and oxycellulose, at two stages of 'nitration,' represented
by 8.2-8.6 p.ct. and 13.5-13.9 p.ct. total nitrogen in the
ester-products, respectively. The results are expressed in terms (c.c.)
of the cupric reagent (Pasteur) reduced per 100 grs. compared with
dextrose (=17767).
Cellulose maximum nitration (13.5 p.ct. N) 3640
Oxycellulose maximum nitration (13.9 p.ct. N) 3600
Cellulose minimum nitration (8.19 p.ct. N) 3700
Oxycellulose minimum nitration (8.56 p.ct. N) 3620
The author concludes that, since the reducing action is independent of
the degree of nitration, and is the same for cellulose and the
oxycelluloses, the ester reaction in the case of the normal cellulose is
accompanied by oxidation, the product being an oxycellulose ester.
_Products of 'denitration'._--The esters were treated with ferrous
chloride in boiling aqueous solution. The products were oxycelluloses,
with a cupric reduction equal to that of an oxycellulose directly
prepared by the action of HClO_{3}. On the other hand, by treatment with
ammonium sulphide at 35°-40° 'denitrated' products were obtained without
action on alkaline copper solutions.
OXYCELLULOSES AND THE MOLECULAR WEIGHT OF CELLULOSE.
H. NASTUKOFF (Berl. Ber. 33 [13] 2237).
(p. 61) The author continues his investigations of the oxidation of
cellulose. [Compare Bull. Mulhouse, 1892.] The products described were
obtained by the action of hypochlorites and permanganates upon Swedish
filter paper (Schleicher and Schüll).
4. _Oxidation by hypochlorites._--(1) The cellulose was digested 24 hrs.
with 35 times its weight of a filtered solution of bleaching power of
4°B.; afterwards drained and exposed for 24 hrs. to the atmosphere.
These treatments were then repeated. After washing, treatment with
dilute acetic acid and again washing, the product was treated with a 10
p.ct. NaOH solution. The oxycellulose was precipitated from the
filtered solution: yield 45 p.ct. The residue when purified amounted to
30 p.ct. of the original cellulose, with which it was identical in all
essential properties.
The oxycellulose, after purification, dried at 110°, gave the following
analytical numbers:
C 43.64 43.78 43.32 43.13
H 6.17 6.21 5.98 6.08
Its compound with phenylhydrazine (_loc. cit._) gave the following
analytical numbers:
N 0.78 0.96 0.84
(2) The reagents were as in (1), but the conditions varied by passing a
stream of carbonic acid gas through the solution contained in a flask,
until Cl compounds ceased to be given off. The analysis of the purified
oxycellulose gave C 43.53, H 6.13.
(3) The conditions were as in (2), but a much stronger hypochlorite
solution--viz. 12°B.--was employed. The yield of oxycellulose
precipitated from solution in soda lye (10 p.ct. NaOH) was 45 p.ct.
There was only a slight residue of unattacked cellulose. The analytical
numbers obtained were:
Oxycellulose C 43.31 43.74 43.69
" H 6.47 6.42 6.51
________________________
Phenylhydrazine compound N 0.62 0.81
B. _Oxidation by permanganate_ (KMnO_{4}). (1) The cellulose 16 grms.
was treated with 1100 c.c. of a 1 p.ct. solution of KMnO_{4} in
successive portions. The MnO_{2} was removed from time to time by
digesting the product with a dilute sulphuric acid (10 p.ct.
H_{2}SO_{4}). The oxycellulose was purified as before, yield 40 p.ct.
Analytical numbers:
Oxycellulose C 42.12 42.9
" H 6.20 6.11
________________________
Phenylhydrazine compound N 1.35 1.08 1.21
(2) The cellulose (16 grms.) was digested 14 days with 2500 c.c. of 1
p.ct. KMnO_{4} solution. The purified oxycellulose was identical in all
respects with the above: yield 40 p.ct. C 42.66, H 6.19.
(3) The cellulose (16 grms.) was heated in the water-bath with 1600 c.c.
of 15 p.ct. H_{2}SO_{4} to which were added 18 grms. KMnO_{4}. The yield
and composition of the oxycellulose was identical with the above. It
appears from these results that the oxidation with hypochlorites acids 1
atom of O to 4-6 of the unit groups C_{6}H_{10}O_{5}; and the oxidation
with permanganate 2 atoms O per 4-6 units of C_{6}H_{10}O_{5}. The
molecular proportion of N in the phenylhydrazine residue combining is
fractional, representing 1 atom O, i.e. 1 CO group reacting per 4
C_{36}H_{60}O_{31} and 6 C_{24}H_{49}O_{21} respectively, assuming the
reaction to be a hydrazone reaction.
Further investigations of the oxycelluloses by treatment with (a)
sodium amalgam, (b) bromine (water), and (c) dilute nitric acid at
110°, led to no positive results.
By treatment with alcoholic soda (NaOH) the products were resolved into
a soluble and insoluble portion, the properties of the latter being
those of a cellulose (hydrate).
_Molecular weight of cellulose and oxycellulose._--The author endeavours
to arrive at numbers expressing these relations by converting the
substances into acetates by Schutzenberger's method, and observing the
boiling-points of their solution in nitrobenzene.
FERMENTATION OF CELLULOSE
V. OMELIANSKI (Compt. Rend., 1897, 125, 1131-1133).
Pure paper was allowed to ferment in the presence of calcium carbonate
at a temperature of 35° for 13 months. The products obtained from
3.4743 grams of paper were: acids of the acetic series, 2.2402 grams;
carbonic anhydride, 0.9722 grams; and hydrogen, 0.0138 gram. The acids
were chiefly acetic and butyric acid, the ratio of the former to the
latter being 1.7 : 1. Small quantities of valeric acid, higher alcohols,
and odorous products were formed.
The absence of methane from the products of fermentation is remarkable,
but the formation of this gas seems to be due to a special organism
readily distinguishable from the ferment that produces the fatty acids.
This organism is at present under investigation.
* * * * *
(p. 75) ~Constitution of Cellulose.~--It may be fairly premised that the
problem of the constitution of cellulose cannot be solved independently
of that of molecular aggregation. We find in effect that the structural
properties of cellulose and its derivatives are directly connected with
their constitution. So far we have only a superficial perception of this
correlation. We know that a fibrous cellulose treated with acids or
alkalis in such a way that only hydrolytic changes can take place is
converted into a variety of forms of very different structural
characteristics, and these products, while still preserving the main
chemical characteristics of the original, show when converted into
derivatives by simple synthesis, _e.g._ esters and sulphocarbonates, a
corresponding differentiation of the physical properties of these
derivatives, from the normal standard, and therefore that the new
reacting unit determines a new physical aggregate. Thus the
sulphocarbonate of a 'hydrocellulose' is formed with lower proportions
of alkaline hydrate and carbon disulphide, gives solutions of relatively
low viscosity, and, when decomposed to give a film or thread of the
regenerated cellulose, these are found to be deficient in strength and
elasticity. Similarly with the acetate. The normal acetate gives
solutions of high viscosity, films of considerable tenacity, and when
those are saponified the cellulose is regenerated as an unbroken film.
The acetates of hydrolysed celluloses manifest a retrogradation in
structural and physical properties, proportioned to the degree of
hydrolysis of the original.
We may take this opportunity of pointing out that the celluloses not
only suggest with some definiteness the connection of the structural
properties of visible aggregates--that is, of matter in the mass--with
the configuration of the chemical molecule or reacting unit, but supply
unique material for the actual experimental investigation of the
problems involved. Of all the 'organic' colloids cellulose is the only
one which can be converted into a variety of derivative forms, from each
of which a regular solid can be produced in continuous length and of any
prescribed dimensions. Thus we can compare the structural properties of
cellulose with those of its hydrates, nitrates, acetates, and benzoates,
in terms of measurements of breaking strain, extensibility, elasticity.
Investigations in this field are being prosecuted, but the results are
not as yet sufficiently elaborated for reduction to formulæ. One
striking general conclusion is, however, established, and that is that
the structural properties of cellulose are but little affected by
esterification and appear therefore to be a function of the special
arrangement of the carbon atoms, i.e. of the molecular constitution.
Also it is established that the molecular aggregate which constitutes a
cellulose is of a resistant type, and undoubtedly persists in the
solutions of the compounds.
It may be urged that it is superfluous to import these questions of
mass-aggregation into the problem of the chemical constitution of
cellulose. But we shall find that the point again arises in attempting
to define the reacting unit, which is another term for the molecule. In
the majority of cases we rely for this upon physical measurements; and
in fact the purely chemical determination of such quantities is
inferential. Attempts have been made to determine the molecular weights
of the cellulose esters in solution, by observations of depression of
solidifying and boiling-points. But the numbers have little value. The
only other well-defined compound is the sulphocarbonate. It has been
pointed out that, by successive precipitations of this compound, there
occurs a continual aggregation of the cellulose with dissociation of the
alkali and CS residues and it has been found impossible to assign a
limit to the dissociation, i.e. to fix a point at which the transition
from soluble sulphocarbonate to insoluble cellulose takes place.
On these grounds it will be seen we are reduced to a somewhat
speculative treatment of the hypothetical ultimate unit group, which is
taken as of C_{6} dimensions.
As there has been no addition of experimental facts directly
contributing to the solution of the problem, the material available for
a discussion of the probabilities remains very much as stated in the
first edition, pp. 75-77. It is now generally admitted that the
tetracetate _n_ [C_{6}H_{6}O.(OAc)_{4}] is a normal cellulose ester;
therefore that four of the five O atoms are hydroxylic. The fifth is
undoubtedly carbonyl oxygen. The reactions of cellulose certainly
indicate that the CO- group is ketonic rather than aldehydic. Even when
attacked by strong sulphuric acid the resolution proceeds some
considerable way before products are obtained reducing Fehling's
solution. This is not easily reconcilable with any polyaldose formula.
Nor is the resistance of cellulose to very severe alkaline treatments.
The probability may be noted here that under the action of the alkaline
hydrates there occurs a change of configuration. Lobry de Bruyn's
researches on the change of position of the typical CO- group of the
simple hexoses, in presence of alkalis, point very definitely in this
direction. It is probable that in the formation of alkali cellulose
there is a constitutional change of the cellulose, which may in effect
be due to a migration of a CO- position within the unit group. Again
also we have the interesting fact that structural changes accompany the
chemical reaction. It is surprising that there should have been no
investigation of these changes of external form and structure, otherwise
than as mass effects. We cannot, therefore, say what may be the
molecular interpretation of these effects. It has not yet been
determined whether there are any intrinsic volume changes in the
cellulose substance itself: and as regards what changes are determined
in the reacting unit or molecule, we can only note a fruitful subject
for future investigation. _A priori_ our views of the probable changes
depend upon the assumed constitution of the unit group. If of the
ordinary carbohydrate type, formulated with an open chain, there is
little to surmise beyond the change of position of a CO- group. But
alternative formulæ have been proposed. Thus the tetracetate is a
derivative to be reckoned with in the problem. It is formed under
conditions which preclude constitutional changes within the unit groups.
The temperature of the main reaction is 30°-40°, the reagents are used
but little in excess of the quantitative proportions, and the yields are
approximately quantitative. If now the derivative is formed entirely
without the hydrolysis the empirical formula C_{6}H_{6}O.(OAc)_{4}
justifies a closed-ring formula for the original viz.
CO<[CHOH]_{4}>CH_{2}; and the preference for this formula depends upon
the explanation it affords of the aggregation of the groups by way of
CO-CH_{2} synthesis.
The exact relationship of the tetracetate to the original cellulose is
somewhat difficult to determine. The starting-point is a cellulose
hydrate, since it is the product obtained by decomposition of the
sulphocarbonate. The degree of _hydrolysis_ attending the cycle of
reactions is indicated by the formula 4 C_{6}H_{10}O_{5}.H_{2}O. It has
been already shown that this degree of hydrolysis does not produce
molecular disaggregation. If this hydrate survived the acetylation it
would of course affect the empirical composition, i.e. chiefly the
carbon percentage, of the product. It may be here pointed out that the
extreme variation of the carbon in this group of carbohydrate esters is
as between C_{14}H_{20}O_{10} (C = 48.3 p.ct.) and C_{14}H_{18}O_{9} (C
= 50.8 p.ct.) i.e. a tetracetate of C_{6}H_{12}O_{6} and
C_{6}H_{10}O_{5} respectively. In the fractional intermediate terms it
is clear that we come within the range of ordinary experimental errors,
and to solve this critical point by way of ultimate analysis must
involve an extended series of analyses with precautions for specially
minimising and quantifying the error. The determination of the acetyl by
saponification is also subject to an error sufficiently large to
preclude the results being applied to solve the point. While, therefore,
we must defer the final statement as to whether the tetracetate is
produced from or contains a partly hydrolysed cellulose molecule, it is
clear that at least a large proportion of the unit groups must be
acetylated in the proportion C_{6}H_{6}O.(OAc)_{4}.
It has been shown that by the method of Franchimont a higher proportion
of acetyl groups can be introduced; but this result involves a
destructive hydrolysis of the cellulose: the acetates are not
derivatives of cellulose, but of products of hydrolytic decomposition.
It appears, therefore, that with the normal limit of acetylation at the
tetracetate the aggregation of the unit groups must depend upon the CO-
groups and a ring formula of the general form CO<[CHOH]_{4}>CH_{2} is
consistent with the facts.
Vignon has proposed for cellulose the constitutional formula
O------CH
| | \
| O \[CHOH]_{3}
| | /
CH_{2}-CH/
with reference to the highest nitrate, and the decomposition of the
nitrate by alkalis with formation of hydroxypyruvic acid. While these
reactions afford no very sure ground for deductions as to constitutional
relationships, it certainly appears that, if the aldose view of the unit
group is to be retained, this form of the anhydride contains suggestions
of the general tendency of the celluloses on treatment with condensing
acids to split off formic acid in relatively large quantity [Ber. 1895,
1940]; the condensation of the oxycelluloses to furfural; the
non-formation of the normal hydroxy-dicarboxylic acids by nitric acid
oxidations. Indirectly we may point out that any hypothesis which
retains the polyaldose view of cellulose, and so fails to differentiate
its constitution from that of starch, has little promise of progress.
The above formula, moreover, concerns the assumed unit group, with no
suggestion as to the mode of aggregation in the cellulose complex. Also
there is no suggestion as to how far the formula is applicable to the
celluloses considered as a group. In extending this view to the
oxycelluloses, Vignon introduces the derived oxidised group
CHO.(CHOH)_{3}.CH . CO
|_O__|
--of which one is apportioned to three or four groups of the cellulose
previously formulated: these groups in condensed union together
constitute an oxycellulose.
These views are in agreement with the experimental results obtained by
Faber and Tollens (p. 71). They regard the oxycelluloses as compounds of
'celloxin' C_{6}H_8{O}_{6} with 1-4 mols. unaltered cellulose; and the
former they particularly refer to as a lactone of glycuronic acid. But
on boiling with lime they obtain dioxybutyric and isosaccharinic acids;
both of which are not very obviously related to the compounds formulated
by Vignon. We revert with preference to a definitely ketonic formula,
for which, moreover, some farther grounds remain to be mentioned. In the
systematic investigation of the nitric esters of the carbohydrates (p.
41) Will and Lenze have definitely differentiated the ketoses from the
aldoses, as showing an internal condensation accompanying the ester
reaction. Not only are the OH groups taking part in the latter
consequently less by two than in the corresponding aldoses, but the
nitrates show a much increased stability. This would give a simple
explanation of the well-known facts obtaining in the corresponding
esters of the normal cellulose. We may note here that an important item
in the quantitative factors of the cellulose nitric ester reaction has
been overlooked: that is, the yield calculated to the NO_{3} groups
fixed. The theoretical yields for the higher nitrates are
Yield p.ct. N p.ct.
of cellulose of nitrate
Pentanitrate 169 12.7
Hexanitrate 183 14.1
From such statistics as are recorded the yields are not in accordance
with the above. There is a sensible deficiency. Thus Will and Lenze
record a yield of 170 p.ct. for a product with 13.8 p.ct. N, indicating
a deficiency of about 10 p.ct. As the by-products soluble in the acid
mixture are extremely small, the deficiency represents approximately the
water split off by an internal reaction. In this important point the
celluloses behave as ketoses.
In the lignocelluloses the condensed constituents of the complex are of
well-marked ketonic, i.e. quinonic, type. In 'nitrating' the
lignocelluloses this phenomenon of internal condensation is much more
pronounced (see p. 131). As the reaction is mainly confined to the
cellulose of the fibre, we have this additional evidence that the
typical carbonyl is of ketonic function. It is still an open question
whether the cellulose constituents of the lignocelluloses are
progressively condensed--with progress of 'lignification'--to the
unsaturated or lignone groups. There is much in favour of this view,
the evidence being dealt with in the first edition, p. 180. The
transition from a cellulose-ketone to the lignone-ketone involves a
simple condensation without rearrangement; from which we may argue back
to the greater probability of the ketonic structure of the cellulose. We
must note, however, that the celluloses of the lignocelluloses are
obtained as residues of various reactions, and are not homogeneous. They
yield on boiling with condensing acids from 6 to 9 p.ct. furfural. It is
usual to regard furfural as invariably produced from a pentose residue.
But this interpretation ignores a number of other probable sources of
the aldehyde. It must be particularly remembered that lævulose is
readily condensed (a) to a methylhydroxyfurfural
C_{6}H_{1}O_{6} - 3H_{2}O = C_{6}H_{6}O_{3} = C_{5}(OH).H_{2}.(CH_{3})O_{2}
and (b) by HBr, with further loss of OH, as under:
C_{6}H_{12}O_{6} - 4H_{2}O + HBr = C_{5}H_{3}(CH_{2}Br)O
and generally the ketoses are distinguished from the aldoses by their
susceptibility to condensation. Such condensation of lævulose has been
effected by two methods: (a) by heating the concentrated aqueous
solution with a small proportion of oxalic acid at 3 atm. pressure
[Kiermayer, Chem. Ztg. 19, 100]; (b) by the action of hydrobromic acid
(gas) in presence of anhydrous ether; the actual compound obtained being
the omega-brommethyl derivative [Fenton, J. Chem. Soc. 1899, 423].
This latter method is being extended to the investigation of typical
celluloses, and the results appear to confirm the view that cellulose
may be of ketonic constitution.
The evidence which is obtainable from the synthetical side of the
question rests of course mainly upon the physiological basis. There are
two points which may be noted. Since the researches of Brown and Morris
(J. Chem. Soc. 1893, 604) have altered our views of the relationships of
starch and cane sugar to the assimilation process, and have placed the
latter in the position of a primary product with starch as a species of
overflow and reserve product, it appears that lævulose must play an
important part in the elaboration of cellulose. Moreover, A. J. Brown,
in studying the cellulosic cell-collecting envelope produced by the
_Bacterium xylinum_, found that the proportion of this product to the
carbohydrate disappearing under the action of the ferment was highest in
the case of lævulose. These facts being also taken into consideration
there is a concurrence of suggestion that the typical CO group in the
celluloses is of ketonic character. That the typical cotton cellulose
breaks down finally under the action of sulphuric acid to dextrose
cannot be held to prove the aldehydic position of the carbonyls in the
unit groups of the actual cellulose molecule or aggregate.
We again are confronted with the problem of the aggregate and as to how
far it may affect the constitution of the unit groups. That it modifies
the functions or reactivity of the ultimate constituent groups we have
seen from the study of the esters. Thus with the direct ester reactions
the normal fibrous cellulose (C_{6}H_{16}O_{5}) yields a monoacetate,
dibenzoate, and a trinitrate respectively under conditions which
determine, with the simple hexoses and anhydrides, the maximum
esterification, i.e. all the OH groups reacting. If the OH groups are of
variable function, we should expect the CO groups _a fortiori_ to be
susceptible of change of function, i.e. of position within the unit
groups.
But as to how far this is a problem of the constitution or phases of
constitution of the unit groups or of the aggregate under reaction we
have as yet no grounds to determine.
The subjoined communication, appearing after the completion of the MS.
of the book, and belonging to a date subsequent to the period intended
to be covered, is nevertheless included by reason of its exceptional
importance and special bearing on the constitutional problem above
discussed.
~THE ACTION OF HYDROGEN BROMINE ON CARBOHYDRATES.~[4]
H. J. H. FENTON and MILDRED GOSTLING (J. Chem. Soc., 1901, 361).
The authors have shown in a previous communication (Trans., 1898, 73,
554) that certain classes of carbohydrates when acted upon at the
ordinary temperature with dry hydrogen bromide in ethereal solution give
an intense and beautiful purple colour.[5] It was further shown (Trans.,
1899, 75, 423) that this purple substance, when neutralised with sodium
carbonate and extracted with ether, yields golden-yellow prisms of
omega-brommethylfurfural,
CH:C.CH_{2}Br
| |
| O
| |
CH:C.CHO.
This reaction is produced by lævulose, sorbose, cane sugar, and inulin,
an intense colour being given within an hour or two. Dextrose, maltose,
milk sugar, galactose, and the polyhydric alcohols give, if anything,
only insignificant colours, and these only after long standing. The
authors therefore suggested that the reaction might be employed as a
means of distinguishing these classes of carbohydrates, the rapid
production of the purple colour being indicative of _ketohexoses_, or of
substances which produce these by hydrolysis.
By relying only on the production of the purple colour, however, a
mistake might possibly arise, owing to the fact that _xylose_ gives a
somewhat similar colour after standing for a few hours. Hence, the
observations should be confirmed by isolation of the crystals of
brommethylfurfural. No trace of this substance is obtained from the
xylose product.
In order to identify the substance, the ether extract, after
neutralisation, is allowed to evaporate to a syrup, and crystallisation
promoted either by rubbing with a glass rod, or by the more certain and
highly characteristic method of 'sowing' with the most minute trace of
omega-brommethylfurfural, when crystals are almost instantly formed.
These are recrystallised from ether, or a mixture of ether and light
petroleum, and further identified by the melting-point (59.5-60.5°),
and, if considered desirable, by estimation of the bromine.
It is now found, so reactive is the bromine atom in this compound, that
the estimation may be accurately made by titration with silver nitrate
according to Volhard's process, the crystals for this purpose being
dissolved in dilute alcohol:
0.1970 gram required 10.5 c.c. _N_/10 AgNO_{3}. Br = 42.63
p.ct., calculated 42.32 p.ct.
This method of applying hydrogen bromide in ethereal solution is, of
course, unsuitable for investigations where a higher temperature has to
be employed, or where long standing is necessary, since, under such
circumstances, the ether itself is attacked. Wishing to make
investigations under these conditions, the authors have tried several
solvents, and, at present, find that chloroform is best suited to the
purpose. In each of the following experiments, 10 grms. of the
substance were covered with 250 c.c. of chloroform which had been
saturated at 0° with dry hydrogen bromide. The mixture was contained in
an accurately stoppered bottle, firmly secured with an iron clamp, and
heated in a water-bath to about the boiling temperature for two hours.
After standing for several hours, the mixture was treated with sodium
carbonate (first anhydrous solid, and afterwards a few drops of strong
solution), filtered, and the solution dried over calcium chloride. Most
of the chloroform was then distilled off, and the remaining solution
allowed to evaporate to a thick syrup in a weighed dish.
The product was then tested for omega-brommethylfurfural by 'sowing'
with the most minute trace of the substance, as described above. It was
then warmed on a water-oven, kept in a vacuum desiccator over solid
paraffin, and the weight estimated. When necessary, the product was
recrystallised from ether, and further identified by the tests
mentioned. The following results were obtained:
Weight of
crude residue.
Swedish filter paper 3.0 crystallised at once by 'sowing.'
Ordinary cotton 3.3 " "
Mercerised cotton 2.1 " "
Straw cellulose[6] 2.3 " "
Lævulose 2.2 " "
Inulin 1.3 " "
Potato starch 0.37 " "
Cane sugar 0.85 " "
Dextrose 0.33 uncrystallisable.
Milk sugar 0.37 "
Glycogen 0.34 "
Galactose 0.34 "
The products from _dextrose_, _milk sugar_, and _galactose_ absolutely
refused to crystallise even when extracted with ether and again
evaporated, or by 'sowing,' stirring, &c.
The _glycogen_ product deposited a very small amount of crystalline
matter on standing, but the quantity was too minute for examination;
moreover, it refused altogether to crystallise in contact with the
aldehyde. It may fairly be stated, therefore, that these last four
substances give absolutely negative results as regards the formation of
omega-brommethylfurfural; if any is formed, its quantity is altogether
too small to be detected.
The specimen of _starch_ examined was freshly prepared from potato, and
purified by digestion for twenty-four hours each with _N_/10 KOH, _N_/4
HCl, and strong alcohol; it was then washed with water and allowed to
dry in the air. It will be seen that this substance gave a positive
result, but that the yield was extremely small, and might yet be due to
impurity. Considering the importance of the behaviour of starch, for the
purpose of drawing general conclusions from these observations, it was
thought advisable to make further experiments with specimens which could
be relied upon, and also to investigate the behaviour of dextrin. This
the authors have been enabled to do upon a series of specimens specially
prepared by C. O'Sullivan, and thus described by him:
1. Rice starch, specially purified by the permanganate method.
2. Wheat starch " " "
3. Oat starch, contains traces of oil, washed with dilute KOH
and dilute HCl.
4. Pea starch, first crop, washed with alkali, acid (HCl), and
strong alcohol.
5. Natural dextrin, D = 3.87, alpha_{D} = 194.7; K = 0.95, (c
2.628).
6. alpha-Dextrin, C equation purified without fermentation, 30
precipitations with alcohol (Trans., 1879, 35, 772).
The examination of these specimens was conducted on a smaller scale, but
under the same conditions as before, _one gram_ of the substance being
treated with 12.5 c.c. of the saturated chloroform solution and heated
in sealed tubes for two hours as above. The results were as follows:
Weight of
crude residue.
1. Rice starch 0.046 crystallised at once by 'sowing.'
2. Wheat starch 0.044 " "
3. Oat starch 0.049 " "
4. Pea starch 0.064 " "
5. Natural dextrin 0.088 " "
6. alpha-Dextrin 0.055 " "
The results may therefore be summarised as follows:--Treated under these
particular conditions all forms of cellulose give large yields of
omega-brommethylfurfural, some varieties giving as much as 33 per cent.
Lævulose, inulin, and cane sugar give yields varying from 22 to 8.5 per
cent.; various starches give small yields (average about 4.5 per cent.);
and dextrins 5 to 8 per cent., whereas dextrose, milk sugar, and
galactose give, apparently, none at all.
The yields represent the solid crystalline residue; this when purified
by recrystallisation gives, probably, about three-quarters of its weight
of pure crystals. (In the case of dextrose, &c., the yields represent
the weight of syrup.)
These numbers, however, by no means represent the maximum yields
obtainable, owing to the comparatively slight solubility of hydrogen
bromide in chloroform. The process was conducted in the above manner
only for the sake of uniform comparison. The ether method previously
described gives much larger yields; for example, 12 grms. of inulin
treated with only 60 c.c. of the saturated ether gave 2.5 grms. of
substance. For the purpose of obtaining larger yields, other methods are
being investigated.
The facts recorded above, taken in conjunction with those given in our
previous communications, appear to point definitely to the following
general conclusions. First, that the various forms of _cellulose_
contain one or more groups or nuclei identical with that contained in
_lævulose_, and that such groups constitute the main or essential part
of the molecule. Secondly, that similar groupings are contained in
_starches_ and _dextrins_, but that the proportion of such groupings
represents a relatively small part of the whole structure.
The nature of this grouping is, according to the generally accepted
constitution of _lævulose_, the six-carbon chain with a ketonic group:
C·C·C·C·C·C
|| .
O
But the results might, on the other hand, be considered indicative of
the anhydride or 'lacton' grouping, which Tollens suggested for
lævulose:
C·C·C·C·C·C
\ /
\ / .
O
The latter very simply represents the formation of
omega-brommethylfurfural from lævulose,[7]
------O-----
| H H |
| | | |
OH·C-----C---C---C--C-----CH_{2}·OH
H_{2} OH OH OH H
giving
H H
HC·C:C·C:C·CH_{2}Br
|| \ / ,
O \ /
O
although by a little further 'manipulation' of the symbols the change
could, of course, be represented by reference to the ketonic formula.
~The Ketonic Constitution of Cellulose.~
C. F. CROSS and E. J. BEVAN (J. Chem. Soc., 1901, 366).
In this paper the authors discuss more fully the theoretical bearings of
the observations of Fenton and Gostling, the two papers being
simultaneously communicated. The paper is mainly devoted to a review of
the antecedent evidence, chemical and physiological, and to a general
summing up in favour of the view that cellulose is a polyketose
(anhydride).
* * * * *
(p. 79) ~Composition of the Seed Hair of Eriodendron~ (~Anf.~)--Some
interest attaches to the results of an analytical investigation which we
have made of this silky floss. There is little doubt that cotton is
entirely exceptional in its characteristics: both in structure and
chemical composition it fails to show any adaptation to what we may
regard as the _more obvious_ functions of a seed hair--which certainly
do not demand either structural strength or chemical resistance. The
following numbers determined for the kapok differentiate it widely from
the cottons:
Ash, 1.3; moisture, 9.3; alkaline hydrolysis (loss) (a) 16.7,
(b) 21.8. Cellulose, by chlorination, &c., 71.1.
In reacting with chloride it shows the presence of unsaturated groups,
similar to the lignone of the woods. This was confirmed by a
well-marked reaction with ferric ferricyanide with increase of weight
due to the fixation of the blue cyanide.
But the most characteristic feature is the high yield of furfural on
boiling with condensing acids. The following numbers were determined:
Total furfural from original fibre 14.84
In residue from alkali hydrolysis 11.5
In cellulose isolated by Cl method 10.4
Treated with sulphuric acids of concentration, (a) 92.1 grs.
H_{2}SO_{4} per 100 c.c., (b) 105.8 grs. per 100 c.c., the fibres
dissolve, and diluted immediately after complete solution it was
resolved into
(a) (b)
Reprecipitated fraction 68.7 43.7
Soluble fraction yielding furfural 13.2 14.3
By these observations it is established that the furfuroids are of the
cellulose type and behave very much as the furfuroids of the cereal
celluloses.
This group of seed hairs invites exhaustive investigation. The furfuroid
constituents are easily isolated, and as they constitute at least
one-third of the fibre substance it is especially from this point of
view that they invite study.
RECHERCHES SUR L'OXYCELLULOSE.
L. VIGNON.
~Résumé of investigations (1898-1900) of Oxycellulose, published as a
brochure~ (Rey, Lyon, 1900).
(a) A typical oxycellulose prepared from cotton cellulose by the
action of HClO_{3} (HCl + KClO_{3}) in dilute solution at 100° for one
hour gave the following numbers:
C H O
Elementary composition 43.55 6.03 50.42
Oxycellulose Original cellulose
Analysis by Lange's method
Soluble in KOH (at 180°) 87.6 12.0
Insoluble in KOH (at 180°) 12.4 88.0
Oxycellulose Original cellulose
Heat of combustion 4124-4133 4190-4224
Heat evolved in contact with 50 times wt.}
normal KOH per 100 grms. } 1.3 cal. 0.74 cal.
Oxycellulose Cellulose
Absorption of colouring } Saffranine 0.7 0.0
matters at 100° per 100 grms. } Methylene blue 0.6 0.2
(b) _Yield of furfural from cellulose, oxy- and
hydro-cellulose._--From the hydrocelluloses variously prepared the
author obtains 0.8 p.ct. furfural; from bleached cotton 1.8 p.ct.; and
from the oxycelluloses variously prepared 2.0-3.5 p.ct. The 'furfuroid'
is relatively more soluble in alkaline solutions (KOH) in the cold. The
insoluble residue is a normal cellulose.
(c) _Nitrates of cellulose, oxy- and hydro-cellulose._--Treated with
the usual acid mixture (H_{2}SO_{4} 3 p., HNO_{3} 1 p.) under conditions
for maximum action, the resulting esters showed uniformly a fixation of
11.0 NO_{2} groups per unit mol. of C_{24}. The oxycellulose nitrate
was treated directly with dilute solution of potassium hydrate in the
cold. From the products of decomposition the author obtained the osazone
of hydroxypyruvic acid [Will, Ber. 24, 400].
(d) _Osazones of the oxycelluloses._--Oxycelluloses prepared by
various methods are found to fix varying proportions of phenylhydrazine
(residue), viz. from 3.4-8.5 p.ct. of the cellulose derivative reacting,
corresponding with, i.e. calculated from, the nitrogen determined in the
products (0.87-2.2 p.ct.). The reaction is assumed to be that of osazone
formation.
The author has also established a relation between the phenylhydrazine
fixed and the furfural which the substance yields on boiling with
condensing acids. This is illustrated by the subjoined series of
numbers:
Phenylhydrazine Furfural
Fixed p.ct. formed p.ct.
Cotton (bleached) 1.73 1.60
Oxycellulose (HClO_{3}) 7.94 2.09
" (HClO) 3.37 1.79
" (CrO_{3}) (1) 7.03 3.00
" (CrO_{3}) (2) 7.71 3.09
" (CrO_{3}) (3) 8.48 3.50
(e) _Constitution of cellulose and oxycellulose._--The results of
these investigations are generalised as regards cellulose (C_6) by the
constitutional formula
CH--CH_{2}
/ | |
(CHOH)_{3} O |
\ | |
CH--O .
The oxycelluloses contain the characteristic group
COH
/
(CHOH)_{3}
\
CH--CO
\ /
O
in union with varying proportions of residual cellulose.
QUANTITATIVE SEPARATION OF CELLULOSE-LIKE CARBOHYDRATES IN VEGETABLE
SUBSTANCES.
WILHELM HOFFMEISTER (Landw. Versuchs-Stat., 1897, 48, 401-411).
To separate the hemicelluloses, celluloses, and the constituents of
lignin without essential change, the substance, after being freed from
fat, is extracted with dilute hydrochloric acid and ammonia, and the
residue frequently agitated for a day or two with 5-6 p.ct. caustic soda
solution. It is then diluted, the extract poured off, neutralised with
hydrochloric acid, treated with sufficient alcohol, and the
hemicellulose filtered, dried, and weighed. The residue from the soda
extract is washed on a filter with hot water, and extracted with
Schweizer's reagent.
When the final residue (lignin) is subjected to prolonged extraction
with boiling dilute ammonia (a suitable apparatus is described, with
sketch) until the ammonia is no longer coloured, a residue is obtained
which mostly dissolves in Schweizer's reagent, and on repeating the
process the residue is found to consist largely of mineral matter. The
dissolved cellulose-like substances often contain considerable amounts
of pentosanes.
According to the nature of the substance, the extraction with ammonia
may take weeks, or months, or even longer; the ammonia extracts of hard
woods (as lignum vitæ) and of cork are dark brown, and give an odour of
vanilla when evaporated down. The residues, which are insoluble in
water, but redissolve in ammonia, have the properties of humic acids.
Other vegetable substances, when extracted, yielded, besides humic
acids, a compound, C_{6}H_{7}O_{2}, soluble in alcohol and chloroform,
but insoluble in water, ether, and benzene; preparations from different
sources melted between 200° and 210°.
FOOTNOTES:
[4] The original paper is reproduced with slight alterations.
[5] This purple colour would appear to be due to a highly dissociable
compound of omega-brommethylfurfural with hydrogen bromide. The aldehyde
gives yellow or colourless solutions in various solvents, which are
turned purple by a sufficient excess of hydrogen bromide. Dilution, or
addition of water, at once discharges the colour.
[6] Other forms of cellulose were also examined--for example, pinewood
cellulose--and the substances separated from solution as thiocarbonate
(powder and film). All of these gave good yields of
omega-brommethylfurfural.
[7] The change is empirically represented as
C_{6}H_{12}O_{6} + HBr - 4H_{2}O = C_{6}H_{5}O_{2}Br.
SECTION IV. CELLULOSE GROUP, INCLUDING HEMICELLULOSES AND TISSUE
CONSTITUENTS OF FUNGI
VERSUCHE ZUR BESTIMMUNG DES GEHALTS EINIGER PFLANZEN UND PFLANZENTEILE
AN ZELLWANDBESTANDTEILEN AN HEMICELLULOSEN UND AN CELLULOSE.
A. KLEIBER (Landw. Vers.-Stat., 1900, 54, 161).
~ON THE DETERMINATION OF CELL-WALL CONSTITUENTS, HEMICELLULOSES AND
CELLULOSE IN PLANTS AND PLANT TISSUES.~
In a preliminary discussion the author critically compares the results
of various of the methods in practice for the isolation and estimation
of cellulose. The method of F. Schulze [digestion with dil. HNO_{3} with
KClO_{3}--14 days, and afterwards treating the product with ammonia,
&c.] is stated to be the 'best known' (presumably the most widely
practised); W. Hoffmeister's modification of the above, in which the
nitric acid is replaced by hydrochloric acid (10 p.ct. HCl) is next
noted as reducing the time of digestion from 14 days to 1-2 days, and
giving in many cases higher yields of cellulose. The methods of treating
with the halogens, viz. bromine water (H. Müller), chlorine gas (Cross
and Bevan), and chlorine water, are dismissed with a bare mention,
apparently on the basis of the conclusions of Suringar and Tollens
(_q.v._). The method of Lange, the basis of which is a 'fusion' with
alkaline hydrates at 180°, and the modified method of Gabriel, in which
the 'fusion' with alkali takes place in presence of glycerin, are
favourably mentioned.
These methods were applied to a range of widely different raw materials
to determine, by critical examination of the products, both as regards
yield and composition, what title these latter have to be regarded as
'pure cellulose.'
This portion of the investigation is an extension of that of Suringar
and Tollens, these latter confining themselves to celluloses of the
'normal' groups, i.e. textile and paper-making celluloses. The present
communication is a study of the tissue and cell-wall constituents of the
following types:--
1. Green plants of false oat grass (_Arrhenatherium, E._).
2. Green plants of lucerne (_Medicago sativa_).
3. Leaves of the ash (_Fraxinus_).
4. Leaves of the walnut (_Juglans_).
5. Roots of the purple melic grass (_Molinia cærulea_).
6. Roots of dandelion (_Taraxacum officinale_).
7. Roots of comfrey.
8. Coffee berries.
9. Wheat bran.
These raw materials were treated for the quantitative estimation of
cellulose by the method of Lange (b), Hoffmeister (c), and Schulze
(d), and the numbers obtained are referred for comparison to the
corresponding yields of 'crude fibre' (Rohfaser) by the standard method
(a).
As a first result the author dismisses Lange's method as hopeless: the
results in successive determinations on the same materials showing
variations up to 60 p.ct. The results by c and d are satisfactorily
concordant: the yields of cellulose are higher than of 'crude fibre.'
This is obviously due to the conservation of 'hemicellulose' products,
which are hydrolysed and dissolved in the treatments for 'crude fibre'
estimation. A modified method was next investigated, in which the
process of digestion with acid chloroxy- compounds (c and d) was
preceded by a treatment with boiling dilute acid. The yields of
cellulose by this method (e) are more uniform, and show less
divergence from the numbers for 'crude fibre.'
The author's numerical results are given in a series of tables which
include determinations of proteids and ash constituents, and the
corresponding deductions from the crude weight in calculating to 'pure
cellulose.' The subjoined extract will illustrate these main lines of
investigation.
___________________________________________________________
| | | |
| | Crude Fibre | Pure Cellulose |
| |_____________|____________________________|
| | | | |
| Raw Material | Weende | Hoffmeister | Hoffmeister, |
| | Method. | Method. | modified by |
| | (a) | (c) | Author. |
| | | | (e) |
|________________|_____________|_____________|______________|
| | | | |
| Oat grass | 30.35 | 34.9 | 31.5 |
| Lucerne | 25.25 | 28.7 | 20.5 |
| Leaves of ash | 13.05 | 15.4 | 13.8 |
| Roots of melic | 21.60 | 29.1 | 21.4 |
| Coffee beans | 18.30 | 35.1 | 23.3 |
| Bran | 8.2 | 19.3 | 9.3 |
|________________|_____________|_____________|______________|
The final conclusion drawn from these results is that the method of
Hoffmeister yields a product containing variable proportions of
hemicelluloses. These are eliminated by boiling with a dilute acid (1.25
p.ct. H_{2}SO_{4}), which treatment may be carried out on the raw
material--i.e. before exposure to the acid chlorate, or on the crude
cellulose as ordinarily isolated.
~Determination of Tissue-constituents.~--By the regulated action of
certain solvents applied in succession, it appears that such
constituents of the plant-complex can be removed as have no organic
connection with the cellular skeleton: the residue from such treatments,
conversely, fairly represents the true tissue-constituents. The author
employs the method of digestion with cold dilute alkaline solutions
(0.15 to 0.5 p.ct. NaOH), followed by exhaustive washing with cold and
hot water, afterwards with cold and hot alcohol, and finally with ether.
The residue is dried and weighed as crude product. When necessary, the
proportions of ash and proteid constituents are determined and deducted
from the 'crude product' which, thus corrected, may be taken as
representing the 'carbohydrate' tissue constituents.
~Determination of Hemicelluloses.~--By the process of boiling with dilute
acids (1.25 p.ct. H_{2}SO_{4}) the hemicelluloses are attacked--i.e.
hydrolysed and dissolved. The action of the acid though selective is, of
course, not exclusively confined to these colloidal carbohydrates. The
proteid and mineral constituents are attacked more or less, and the
celluloses themselves are not entirely resistant to the action. The loss
due to the latter may be neglected, but in calculating the hemicellulose
constants from the gross loss the proteids and mineral constituents
require to be taken into account in the usual way.
QUANTITATIVE SEPARATION OF HEMICELLULOSE, CELLULOSE, AND LIGNIN.
PRESENCE OF PENTOSANES IN THESE SUBSTANCES.
WILHELM HOFFMEISTER (Landw. Versuchs-Stat, 1898, 50, 347-362).
(p. 88) The separation of the cellulose-like carbohydrates of sunflower
husks is described.
In order to ascertain the effect of dilute ammonia on the cellulose
substances of lignin, a dried 5 p.ct. caustic soda extract was extracted
successively with 1, 2, 3, and 4 p.ct. sodium hydroxide solution. Five
grams of the 2 p.ct. extract were then subjected to the action of
ammonia vapour; the cellulose did not completely dissolve in six weeks.
Cellulose insoluble in caustic soda (32 grms.) was next extracted with
ammonia, in a similar manner, for 10 days, dried, and weighed. 30.46
grms. remained, which, when treated with 5 p.ct. aqueous caustic soda,
yielded 0.96 grm. (3 per cent.) of hemicellulose.
When cellulose is dissolved in Schweizer's solution, the residue is, by
repeated extraction with aqueous sodium hydroxide, completely converted
into the soluble form. On evaporating the ammonia from the Schweizer's
extract, at the ordinary temperature and on a water-bath respectively,
different amounts of cellulose are obtained; more hemicellulose is
obtained, by caustic soda, from the heated solution than from that which
was not heated. In this operation the pentosanes are more influenced
than the hexosanes; pentosanes are not always readily dissolved by
caustic soda, and hexosanes are frequently more or less readily
dissolved. Both occur in lignin, and are then undoubtedly indigestible.
These points have to be considered in judging the digestibility of these
carbohydrates.
A comparison of analyses of clover, at different periods, in the first
and second years of growth, shows that both cellulose (Schweizer's
extract) and lignin increase in both constituents. In the second year
the lignin alone increased to the end; the cellulose decreased at the
end of June. In the first year it seemed an absolutely as well as
relatively greater amount of cellulose, and lignin was produced in the
second year; this, however, requires confirmation. The amount of
pentosanes in the Schweizer extract was relatively greater in the second
than in the first year, but decreased in the lignin more in the second
year than in the first: this result is also given with reserve.
DIE CONSTITUTION DER CELLULOSEN DER CEREALIEN.
C. F. CROSS, E. J. BEVAN, and C. SMITH (Berl. Ber., 1896, 1457).
~THE CONSTITUTION OF THE CEREAL CELLULOSES.~
(p. 84) Straw cellulose is resolved by two methods of acid hydrolysis
into a soluble furfural-yielding fraction, and an insoluble fraction
closely resembling the normal cellulose. (a) The cellulose is
dissolved in sulphuric acids of concentration, H_{2}SO_{4}.2H_{2}O,
H_{2}SO_{4}.3H_{2}O. As soon as solution is complete, the acid is
diluted. A precipitate of cellulose hydrate (60-70 p.ct.) is obtained,
and the filtered solution contains 90-95 p.ct. of the furfuroids of the
original cellulose. The process is difficult to control, however, in
mass, and to obtain the latter in larger quantity the cellulose (b) is
digested with six times its weight of 1 p.ct. H_{2}SO_{4} at 3 atm.
pressure, the products of the action being (1) a disintegrated cellulose
retaining only a small fraction (1/12) of the furfural-yielding groups,
and (2) a slightly coloured solution of the hydrolised furfuroids. An
investigation of the latter gave the following results: By oxidation
with nitric acid no saccharic acid was obtained; showing the absence of
dextrose. The numbers for cupric reduction were in excess of those
obtained with the hexoses. The yield of ozazone was high, viz. 30 to 40
p.ct. of the weight of the carbohydrate in solution. On fractionating,
the melting-points of the fractions were found to lie between 146° and
153°. Ultimate analysis gave numbers for C, H, and N identical with
those of a pentosazone. The product of hydrolysis appears, therefore, to
be xylose or a closely related derivative.
All attempts to obtain a crystallisation of xylose from the solution
neutralised (BaCO_{3}), filtered, and evaporated, failed. The reaction
with phloroglucol and HCl, moreover, was not the characteristic red of
the pentoses, but a deep violet. The product was then isolated as a dry
residue by evaporating further and drying at 105°. Elementary analysis
gave the numbers C 44.2, 44.5, and H 6.7, 6.3. Determinations of
furfural gave 39.5 to 42.5 p.ct. On treating the original solution with
hydrogen peroxide, and warming, oxidation set in, with evolution of
CO_{2}. This was estimated (by absorption), giving numbers for CO_{2},
19.5, 20.5, 20.1 p.ct. of the substance.
The sum of these quantitative data is inconsistent with a pentose or
pentosane formula; it is more satisfactorily expressed by the empirical
formula
O
/ \
C_{5}H_{8}O_{3} CH_{2},
\ /
O
which represents a pentose monoformal. Attempts to synthesise a compound
of this formula have been so far without success.
UEBER EINIGE CHEMISCHE VORGÄNGE IN DER GERSTENPFLANZE.
C. F. CROSS, E. J. BEVAN, and C. SMITH (Berl. Ber., 1895, 2604).
~THE CHEMICAL LIFE-HISTORY OF THE BARLEY PLANT.~
(p. 84) Owing to the presence of 'furfuroids' in large proportion as
constituents of the tissues of the stems of cereals, these plants afford
convenient material for studying the problem of the constitution of the
tissue-furfuroids, as well as their relationship to the normal
celluloses. The growing barley plant was investigated at successive
periods of growth. Yield of furfural was estimated on the whole plant
and on the residue from a treatment with alkaline and acid solvents in
the cold such as to remove all cell contents. This residue is described
as 'permanent tissue.' The observations were carried out through two
growing seasons--1894-5--which were very different in character, the
former being rainy with low temperature, the latter being abnormal in
the opposite direction, i.e. minimum rainfall and maximum sunshine. The
barley selected for observation was that of two experimental plots of
the Royal Agricultural Society's farm, one (No. 1) remaining permanently
unmanured, and showing minimum yield, the other (No. 6) receiving such
fertilising treatment as to give maximum yields.
The numerical results are given in the annexed tables:
Table Headings:
A: Date
B: Age of Crop
C: Plot
D: Dry Weight
E: Furfural p.ct. of dry weight (a)
F: Permanent tissue p.ct. dry weight
G: Furfural from permanent tissue
H: P.ct. of tissue
I: P.ct. of entire plant
J: Ratio a : c
BARLEY CROP, WOBURN, 1894.
________________________________________________________________________
| | | | | | | | |
| | | | | | | [G] | |
| | | | | | |_____________| |
| | | | | | | | | |
| [A] | [B] | [C] | [D] | [E] | [F] | [H] | [I] | [J] |
|_________|__________|_____|______|______|______|______|______|__________|
| | | | | | | | | |
| May 7 | 6 weeks | 1 | 19.4 | 7.0 | 53.4 | 12.7 | 6.8 | 1.03 : 1 |
| | | 6 | 14.7 | 7.0 | 55.9 | 10.3 | 5.7 | 1.23 : 1 |
| June 4 | 10 weeks | 1 | 17.6 | 7.7 | 52.9 | 11.6 | 6.1 | 1.26 : 1 |
| | | 6 | 13.5 | 8.1 | 58.5 | 13.4 | 7.8 | 1.04 : 1 |
| July 10 | 15 weeks | 1 | 42.0 | 9.0 | 65.7 | 9.8 | 6.4 | 1.40 : 1 |
| | | 6 | 32.9 | 10.6 | 65.7 | 12.5 | 8.2 | 1.30 : 1 |
| Cut | 21 weeks | 1 | 64.0 | 11.9 | 70.0 | 14.5 | 10.1 | 1.18 : 1 |
| Aug. 21 | | 6 | 64.6 | 13.4 | 70.5 | 15.0 | 10.6 | 1.26 : 1 |
| Carried | 22 weeks | 1 | 84.0 | 12.7 | 75.0 | 16.5 | 12.4 | 1.02 : 1 |
| Aug. 31 | | 6 | 86.4 | 12.4 | 78.4 | 15.1 | 11.8 | 1.05 : 1 |
| |
| BARLEY CROP, WOBURN, 1895. |
| |
| May 15 | 7 weeks | 1 | 20.6 | 6.6 | 53.9 | 10.2 | 5.5 | 1.20 : 1 |
| | | 6 | 17.8 | 5.8 | 56.7 | 9.6 | 5.4 | 1.07 : 1 |
| June 18 | 12 weeks | 1 | 34.6 | 8.0 | 38.2 | 14.7 | 5.6 | 1.42 : 1 |
| | | 6 | 33.4 | 7.6 | 44.5 | 15.0 | 6.7 | 1.14 : 1 |
| July 16 | 16 weeks | 1 | 52.8 | 12.1 | 55.6 | 16.3 | 9.1 | 1.33 : 1 |
| | | 6 | 54.4 | 10.6 | 46.2 | 19.1 | 8.8 | 1.20 : 1 |
| Aug. 16 | 20 weeks | 1 | 66.8 | 9.2 | 49.1 | 17.0 | 8.3 | 1.10 : 1 |
| | | 6 | 65.0 | 9.8 | 49.8 | 19.1 | 9.4 | 1.04 : 1 |
| Sept. 3 | 22 weeks | 1 | 84.3 | 10.4 | 45.7 | 17.6 | 8.0 | 1.31 : 1 |
| | | 6 | 86.3 | 10.2 | 45.3 | 17.3 | 7.8 | 1.30 : 1 |
|_________|__________|_____|______|______|______|______|______|__________|
The variations exhibited by these numbers are significant. It is clear,
on the other hand, that the assimilation of the furfuroids does not vary
in any important way with variations in conditions of atmosphere and
soil nutrition. They are essentially _tissue_-constituents, and only at
the flowering period is there any accumulation of these compounds in the
alkali-soluble form. It has been previously shown (ibid. 27, 1061)
that the proportion of furfuroids in the straw-celluloses of the
paper-maker differs but little from that of the original straws. For the
isolation of the celluloses the straws are treated by a severe process
of alkaline hydrolysis, to which, therefore, the furfuroid groups offer
equal resistance with the normal hexose groups with which they are
associated in the complex.
The furfuroids of the cereal straws are therefore not pentosanes. They
are original products of assimilation, and not subject to secondary
changes after elaboration such as to alter either their constitution or
their relationship to the normal hexose groups of the tissue-complex.
(1) CONSTITUTION OF THE CEREAL CELLULOSES
(Chem. Soc. J. 1896, 804).
(2) THE CARBOHYDRATES OF BARLEY STRAW
(Chem. Soc. J. 1896, 1604).
(3) THE CARBOHYDRATES OF THE CEREAL
STRAWS (Chem. Soc. J. 1897, 1001).
(4) THE CARBOHYDRATES OF BARLEY STRAW
(Chem. Soc. J. 1898, 459).
C. F. CROSS, E. J. BEVAN, and CLAUD SMITH.
These are a series of investigations mainly devoted to establishing the
identity of the furfural-yielding group which is a characteristic
constituent.
This 'furfuroid' while equally resistant to alkalis as the normal
cellulose group with which it is associated, is selectively hydrolysed
by acids. Thus straw cellulose dissolves in sulphuric acids of
concentration H_{2}SO_{4}.2H_{2}O - H_{2}SO_{4}.3H_{2}O, and on diluting
the normal cellulose is precipitated as a hydrate, and the furfuroid
remains in solution. But this sharp separation is difficult to control
in mass. By heating with a very dilute acid (1 p.ct. H_{2}SO_{4}) the
conditions are more easily controlled, the most satisfactory results
being obtained with 15 mins. heating at 3 atm. pressure.
(1) Operating in this way upon brewers' grains the furfuroid was
obtainable as the chief constituent of a solution for which the
following experimental numbers were determined:--Total dissolved solids,
28.0 p.ct. of original 'grains'; furfural, 39.5 p.ct. of total dissolved
solids, as compared with 12.5 p.ct. of total original grains; cupric
reduction (calc. to total solids), 110 (dextrose = 100) osazone; yield
in 3 p.ct. solution, 35 p.ct. of weight of total solids.
Pentosazone
Analysis N 17.1 17.3 17.07
C 62.5 62.3 62.2
H 6.4 6.5 6.1
Melting-point 146°-153°
From these numbers it is seen that of the total furfuroids of the
original 'grains' 84 p.ct. are thus obtained in solution in the fully
hydrolysed form, which is that of a pentose or pentose derivative. It
was, however, found impossible to obtain any crystallisation from the
neutralised (BaCO_{3}) and concentrated solution, the syrup being kept
for some weeks in a desiccator. It was noted at the same time that the
colour reaction of the original solution with phloroglucol and
hydrochloric acid was a deep violet, in contradistinction to the
characteristic red of the pentoses. On oxidation with hydrogen peroxide,
in the proportion of 1 mol. H_{2}O_{2} to 1 mol. of the carbohydrate in
solution, carbonic anhydride was formed in quantity = 20.0 p.ct. of the
latter.
Fermentation (yeast) experiments also showed a divergence from the
resistant behaviour of the pentoses, a considerable proportion of the
furfuroid disappearing in a normal fermentation.
(2) The quantitative methods above described were employed in
investigating the barley plant at different stages of its growth. The
green plant was extracted with alcohol, the residue freed from alcohol
and subjected to acid hydrolysis.
The hydrolysed extract was neutralised and fermented. In the early
stages of growth the furfuroids were completely fermented, i.e.
disappeared in the fermentation. In the later stages this proportion
fell to 50 p.ct. In the earlier stages, moreover, the normal hexose
constituents of the permanent tissue were hydrolysed in large proportion
by the acid, whereas in the matured straw the hydrolysis is chiefly
confined to the furfuroids. In the early stages also the permanent
tissue yields an extract with relatively low cupric reduction, showing
that the carbohydrates are dissolved by the acid in a more complex
molecular condition.
These observations confirm the view that the furfuroids take origin in a
hexose-pentose series of transformations. The proportion of furfuroid
groups to total carbohydrates varies but little, viz. from 1/3 in the
early stages to a maximum of 1/4 at the flowering period. At this period
the differentiation of the groups begins to be marked.
Taking all the facts of (1) and (2), they are not inconsistent with the
hypothesis of an internal transformation of a hexose to a
pentose-monoformal. Such a change of position and function of oxygen
from OH to CO within the group --CH.OH-- is a species of internal
oxidation which reverses the reduction of formaldehyde groups in
synthesising to sugars, and appears therefore of probable occurrence.
These constitutional problems are followed up in (3) by the indirect
method of differentiating the relationships of these furfuroids to yeast
fermentation, from those of the pentoses. Straw and esparto celluloses
are subjected to the processes of acid hydrolysis, and the neutralised
extracts fermented. With high furfural numbers indicating that the
furfuroids are the chief constituents of the extract, there is an active
fermentation with production of alcohol. The cupric reduction falls in
greater ratio to the original (unfermented) than the furfural.
Observations on the pure pentoses--xylose and arabinose added to
dextrose solutions, and then exposed to yeast action--show that in a
vigorous fermentation not unduly prolonged the pentoses are unaffected,
but that they do come within the influence of the yeast-cell when the
latter is in a less vigorous condition, and when the hexoses are not
present in relatively large proportion.
(4) The observations on the growing plant were resumed with the view of
artificially increasing the differentiation of the two main groups of
carbohydrates. From a portion of a barley crop the inflorescence was
removed as soon as it appeared. The crop was allowed to mature, and a
full comparison instituted between the products of normal and abnormal
growth. With a considerable difference in 'permanent tissue' (13 p.ct.
less) and a still greater defect in cellulose (24 p.ct.), the constants
for the furfuroids in relation to total carbohydrates were unaffected by
the arrested development. This was also true of the behaviour of the
hydrolysed extracts (acid processes) to yeast fermentation.
(5) The extract obtained from the brewers' grains by the process
described in (2) was investigated in relation to animal digestion. It
has been now generally established that the furfuroids as constituents
of fodder plants are digested and assimilated in large proportion in
passing through animal digestive tracts, and in this respect behave
differently from the pentoses. The furfuroids being obtained, as
described, in a fully hydrolysed condition (monoses) the digestion
problem presented itself in a new aspect, and was therefore attacked.
The result of the comparative feeding experiments upon rabbits was to
show that in this previously hydrolysed form the furfuroids are almost
entirely digested and assimilated, no pentoses, moreover, appearing in
the urine.
Generally we may sum up the present solution of the problem of the
relationship of the furfuroids to plant assimilation and growth as
follows:--The pentoses are not produced as such in the process of
assimilation; but furfural-yielding carbohydrates are produced directly
and in approximately constant ratio to the total carbohydrates; they are
mainly located in the permanent tissue; in the secondary changes of
dehydration, &c., accompanying maturation they undergo such
differentiation that they become readily separable by processes of acid
hydrolysis from the more resistant normal celluloses; but in relation to
alkaline treatments they maintain their intimate union with the latter.
They are finally converted into pentoses by artificial treatments, and
into pentosanes in the plant, with loss of 1 C atom in an oxidised form.
The mechanism of this transformation of hexoses into pentoses is not
cleared up. It is independent of external conditions, e.g.
fertilisation and atmospheric oxidations, and is probably therefore a
process of internal rearrangement of the character of an oxidation.
ZUR KENNTNISS DER IN DEN MEMBRANEN DER PILZE ENTHALTENEN BESTANDTHEILE.
E. WINTERSTEIN (Ztschr. Physiol. Chem., 1894, 521; 1895, 134).
~ON THE CONSTITUENTS OF THE TISSUE OF FUNGI.~
(p. 87) These two communications are a contribution of fundamental
importance, and may be regarded as placing the question of the
composition of the celluloses of these lowest types on a basis of
well-defined fact. In the first place the author gives an exhaustive
bibliography, beginning with the researches of Braconnot (1811), who
regarded the cellular tissue of these organisms as a specialised
substance, which he termed 'fungin.' Payen rejects this view, and
regards the tissue, fully purified by the action of solvents, as a
cellulose (C_{6}H_{10}O_{5}). This view is successively supported by
Fromberg [Mulder, Allg. Phys. Chem., Braunschweig, 1851], Schlossberger
and Doepping [Annalen, 52, 106], and Kaiser. De Bary, on a review of the
evidence, adopts this view, but, as the purified substance fails to give
the characteristic colour-reactions with iodine, he uses the qualifying
term 'pilzcellulose' [Morph. u. Biol. d. Pilze u. Flechten, Leipzig,
1884].
C. Richter, on the other hand, shows that these reactions are merely a
question of methods of purification or preparation [Sitzungsber. Acad.
Wien, 82, 1, 494], and considers that the tissue-substance is an
ordinary cellulose, with the ordinary reactions masked by the presence
of impurities. In regard to the lower types of fungoid growth, such as
yeast, the results of investigators are more at variance. The researches
of Salkowski (p. 113) leave little doubt, however, that the
cell-membrane is of the cellulosic type.
The author's researches extend over a typical range of products obtained
from _Boletus edulis, Agaricus campestris, Cantharellus cibarius,
Morchella esculenta, Polyporus officinalis, Penicillium glaucum_, and
certain undetermined species. The method of purification consisted
mainly in (a) exhaustive treatments with ether and boiling alcohol,
(b) digestion with alkaline hydrate (1-2 p.ct. NaOH) in the cold,
(c) acid hydrolysis (2-3 p.ct. H_{2}SO_{4}) at 95°-100°, followed by a
chloroxidation treatment by the processes of Schulze or Hoffmeister, and
final alkaline hydrolysis.
The products, i.e. residues, thus obtained were different in essential
points from the celluloses isolated from the tissues of phanerogams
similarly treated. Only in exceptional cases do they give blue reactions
with iodine in presence of zinc chloride or sulphuric acid. The
colourations are brown to red. They resist the action of cuprammonium
solutions. They are for the most part soluble in alkaline hydrate
solution (5-10 p.ct. NaOH) in the cold. They give small yields (1-2
p.ct.) of furfural on boiling with 10 p.ct. HCl.Aq.
Elementary analyses gave the following results, which are important in
establishing the presence of a notable proportion of nitrogen, which has
certainly been overlooked by the earlier observers:--
_________________________________________________________
| | | | |
| 'Cellulose' or residue from | C | H | N |
|______________________________________|______|_____|_____|
| | | | |
| Boletus edulis (Schulze process) | 42.4 | 6.5 | 3.9 |
| Boletus edulis (Hoffmeister process) | 44.6 | 6.3 | 3.6 |
| Polyporus off. | 43.7 | 6.5 | 0.7 |
| Cantharellus cib. | 44.9 | 6.8 | 3.0 |
| Agaricus campestris | 44.3 | 6.6 | 3.6 |
| Botrytis | 42.1 | 6.3 | 3.9 |
| Penicillium glaucum | | | 3.3 |
| Morchella esculenta | | | 2.5 |
|______________________________________|______|_____|_____|
It is next shown that this residual nitrogen is not in the form of
residual proteids (1) by direct tests, all of which gave negative
results, and (2) indirectly by the high degree of resistance to both
alkaline and acid hydrolysis. The 'celluloses' are attacked by boiling
dilute acids (1 p.ct. H_{2}SO_{4}), losing in weight from 10 to 23
p.ct., the dissolved products having a cupric reduction value about 50
p.ct. that of an equal weight of dextrose. As an extreme hydrolytic
treatment the products were dissolved in 70 p.ct. H_{2}SO_{4}, allowed
to stand 24 hours, then considerably diluted (to 3 p.ct. H_{2}SO_{4})
and boiled to complete the inversion. The yields of glucose, calculated
from the cupric reduction, were as follows:--
Boletus edulis 65.2 p.ct.
Polyporus off. 94.7 "
Agaricus campestris 59.1 "
Morchella esculenta 60.1 "
Cantharellus cib. 64.9 "
Botrytis 60.8 "
It will be noted that the exceptionally high yield from the Polyporus
cellulose is correlated with its exceptionally low nitrogen. By actual
isolation of a crystalline dextrorotary sugar, by preparations of
osazone and conversion into saccharic acid, it was proved that dextrose
was the main product of hydrolysis. The second main product was shown to
be acetic acid, the yield of which amounted to 8 p.ct. in several cases.
Generally, therefore, it is proved that the more resistant tissue
constituents of the fungi are not cellulose, but a complex of
carbohydrates and nitrogenous groups in combination, the former being
resolved into glucoses by acid hydrolysis, and the latter yielding
acetic acid as a characteristic product of resolution together with the
nitrogenous groups in the form of an uncrystallisable syrup.
In the further prosecution of these investigations (2) the author
proceeded from the supposition of the identity of the nitrogenous
complex of the original with chitin, and adopted the method of
Ledderhose (Ztschr. Physiol. Chem. 2, 213) for the isolation of
glucosamin hydrochloride, which he succeeded in obtaining in the
crystalline form. In the meantime E. Gilson had shown that these tissue
substances in 'fusion' with alkaline hydrates yield a residue of a
nitrogenous product (C_{14}H_{28}N_{2}O_{10}), which is soluble in
dilute acids [Recherches Chim. sur la Membrane Cellulaire des
Champignons, La Cellule, v. II, pt. 1]. This residue, which was termed
mycosin by Gilson, has been similarly isolated by the author. It is
proved, therefore, that the tissues of the fungi do contain a product
resembling chitin. [See also Gilson, Compt. Rend. 120, 1000.] This
constituent is in intimate union with the carbohydrate complex, which is
resolved similarly to the hemicelluloses. Various intermediate terms of
the hydrolytic series have been isolated. But the only fully identified
product of resolution is the dextrose which finally results.
UEBER DIE KOHLENHYDRATE D. HEFE.
E. SALKOWSKI (Berl. Ber., 27, 3325).
~ON THE CARBOHYDRATES OF YEAST.~
The author has isolated the more resistant constituents of the
cell-membrane by boiling with dilute alkalis, and exhaustively purifying
with alcohol and ether.
The residue was only a small percentage (3-4 p.ct) of the original, and
retained only 0.45 p.ct. N.
It was heated in a digester with water at 2-3 atm. steam-pressure, and
thus resolved into approximately equal portions of soluble cellulose
(a) and insoluble (b). The latter, giving no colour-reaction with
iodine, is termed achroocellulose; the former reacts, and is therefore
termed erythrocellulose. The former is easily separated from its
opalescent solution. It has the empirical composition of cellulose. In
the soluble form it resembles glycogen. The achroocellulose is isolated
in the form of horny or agglomerated masses. It appears to be resolved
by ultimate hydrolysis into dextrose and mannose.
SECTION V. FURFUROIDS, i.e. PENTOSANES AND FURFURAL-YIELDING
CONSTITUENTS GENERALLY
(1) ~Reactions of the Carbohydrates with Hydrogen Peroxide.~
C. F. CROSS, E. J. BEVAN, and CLAUD SMITH (J. Chem. Soc., 1898, 463).
(2) ~Action of Hydrogen Peroxide on Carbohydrates in the Presence of
Ferrous Salts.~
R. S. MORRELL and J. M. CROFTS (J. Chem. Soc., 1899, 786).
(3) ~Oxidation of Furfuraldehyde by Hydrogen Peroxide.~
C. F. CROSS, E. J. BEVAN, and T. HEIBERG (J. Ch. Soc., 1899, 747).
(4) EINWIRKUNG VON WASSERSTOFFHYPEROXID AUF UNGESÄTTIGTE
KOHLENWASSERSTOFFE.
C. F. CROSS, E. J. BEVAN, and T. HEIBERG (Berl. Ber., 1900, 2015).
~ACTION OF HYDROGEN PEROXIDE ON UNSATURATED HYDROCARBONS.~
The above series of researches grew out of the observations incidental
to the use of the peroxide on an oxidising agent in investigating the
hydrolysed furfuroids (102). Certain remarkable observations had
previously been made by H. J. H. Fenton (Ch. Soc. J., 1894, 899; 1895,
774; 1896, 546) on the oxidation of tartaric acid by the peroxide,
acting in presence of ferrous salts, the --CHOH--CHOH-- residue losing
H_{2} with production of the unsaturated group, --OH.C=C.OH--. These
investigations have subsequently been considerably developed and
generalised by Fenton, but as the results have no immediate bearing on
our main subject we must refer readers to the J. Chem. Soc., 1896-1900.
From the mode of action diagnosed by Fenton it was to be expected that
the CHOH groups of the carbohydrates would be oxidised to CO groups, and
it has been established by the above investigations (1) and (2) that the
particular group to be so affected in the hexoses is that contiguous to
the typical
|
--CO
group. There results, therefore, a dicarbonyl derivative ('osone'),
which reacts directly with 2 mol. phenyl hydrazine in the cold to form
an osazone. This was directly established for glucose, lævulose,
galactose, and arabinose (2). While this is the main result, the general
study of the product shows that the oxidation is not simple nor in
direct quantitative relationship to the H_{2}O_{2} employed. The
molecular proportion of the aldoses affected appears to be in
considerable excess, and the reaction is probably complicated by
interior rearrangement.
In the main, the original aldehydic group resists the oxidation. But a
certain proportion of acid products are formed, probably tartronic acid.
On distillation with condensing acids a large proportion of volatile
monobasic acids (chiefly formic) are obtained. The proportion of
furfural obtained amounts to 3-4 per cent. of the weight of the original
carbohydrate.
Since the general result of these oxidations is the substitution of an
OH group for an H atom, it was of interest to determine the behaviour of
furfural with the peroxide. The oxidation was carried out in dilute
aqueous solution of the aldehyde at 20°-40°, using 2-3 mols. H_{2}O_{2}
per 1 mol. C_{5}H_{4}O_{2}. The main product is a hydroxyfurfural, which
was separated as a hydrazone. A small quantity of a monobasic acid was
formed, which was identified as a hydroxypyromucic acid. Both aldehyde
and acid appear to be the alpha beta derivatives. The aldehyde gives
very characteristic colour reactions with phloroglucinol and resorcinol
in presence of hydrochloric acid, which so closely resemble those of the
lignocelluloses that there is little doubt that these particular
reactions must be referred to the presence of the hydroxyfurfural as a
normal constituent.
The study of these oxidations was then extended to typical unsaturated
hydrocarbons--viz. acetylene and benzene. (4) From the former the main
product was acetic acid, but the attendant formation of traces of ethyl
alcohol indicates that the hydrogen of the peroxide may take a direct
part in this and other reactions. This view receives some support from
the fact that the interaction of the H_{2}O_{2} with permanganates has
now been established to be an oxidation of the H_{2} of the peroxide by
the permanganate oxidation, with liberation, therefore, of the O_{2} of
the peroxide as an unresolved molecule [Baeyer].
Benzene itself is also powerfully attacked by the peroxide when shaken
with a dilute solution in presence of iron salts. The products are
phenol and pyrocatechol, with some quantity of an amorphous product
probably formed by condensation of a quinone with the phenolic products
of reaction.
* * * * *
These types of oxidation effects now established give a definite
significance to the physiological functions of the peroxide, which is a
form of 'active oxygen' of extremely wide distribution. It would have
been difficult _a priori_ to devise an oxidant without sensible action
on aldehydic groups, yet delivering a powerful attack on hydrocarbon
rings; or to have suggested a synthesis of the sugars from tartaric acid
with a powerful oxidising treatment as the first and essential stage in
the transformation.
Our present knowledge of such actions and effects suggests a number of
new clues to genetic relationships of carbon compounds within the plant.
The conclusion is certainly justified that the origin of the pentoses is
referable to oxidations of the hexoses, in which this form of 'active
oxygen' plays an important part.
We must note here the researches of O. Ruff, who has applied these
oxidations with important results in the systematic investigation of the
carbohydrates.
UEBER DIE VERWANDLUNG DER _D_-GLUCONSÄURE IN _D_-ARABINOSE (Berl. Ber.,
1898, 1573).
~CONVERSION OF _D_-GLUCONIC ACID INTO _D_-ARABINOSE.~
* * * * *
_D_ UND _L_ ARABINOSE (_Ibid._ 1899, 550).
* * * * *
ZUR KENNTNISS DER OXYGLUCONSÄURE (_Ibid._ 1899, 2269).
~ON OXYGLUCONIC ACID.~
Ruff in these researches has realised a simple and direct transition
from the hexoses to the pentoses. By oxidising gluconic acid with the
peroxide the beta --CHOH-- group is converted into carbonyl at the same
time that the terminal COOH [alpha] is oxidised to CO_{2}. The yields of
the resulting pentose are large. Simultaneously there is formed an
oxygluconic acid, which appears to be a ketonic acid of formula
--CH_{2}OH.CO.(CHOH)_{3}.COOH--.
From these results we see a further range of physiological
probabilities; and with the concurrent actions of oxygen in the forms of
or related to hydrogen peroxide on the one side, and ozone on the other,
we are able to account in a simple way for the relationships of the
'furfuroid' group, which may include a number of intermediate terms in
the hexose-pentose series.
Following in this direction of development of the subject is a study of
the action of persulphuric acid upon furfural.
EINWIRKUNG DES CARO'SCHEN REAGENS AUF FURFURAL.
C. F. CROSS, E. J. BEVAN, and J. F. BRIGGS (Berl. Ber., 1900, 3132).
Regarding this reagent as another form of 'active oxygen,' it is
important to contrast its actions with those of the hydrogen peroxide.
Instead of the beta-hydroxyfurfural (_ante_, 115) we obtain the
delta-aldehyde as the first product. The aldehydic group is then
oxidised, and as a result of attendant hydrolysis the ring is broken
down and succinic acid is formed, the original aldehydic group of the
furfural being split off in the form of formic acid. The reactions take
place at the ordinary temperature and with the dilute form of the
reagent described by Baeyer and Villiger (Ber. 32, 3625). These results
have some special features of interest. The alpha delta-hydroxyfurfural
has similar colour reactions to those of the alpha beta-derivative, and
may also therefore be present as a constituent of the lignocelluloses.
The tendency to attack in the 1·4 position in relation to an aldehydic
group further widens the capabilities of 'active oxygen' in the plant
cell. Lastly, this is the simplest transition yet disclosed from the
succinyl to furfural grouping, being effected by a regulated proportion
of oxygen, and under conditions of reaction which may be described as of
the mildest. In regard to the wide-reaching functions of asparagin in
plant life, we have a new suggestion of genetic connections with the
furfuroids.
VERGLEICH DER PENTOSEN-BESTIMMUNGSMETHODEN VERMITTELST PHENYLHYDRAZIN
UND PHLOROGLUCIN.
M. KRÜGER (Inaug.-Diss., Göttingen, 1895).
~COMPARISON OF METHODS OF ESTIMATING FURFURAL AS HYDRAZONE AND
PHLOROGLUCIDE.~
The author traces the development of processes of estimating furfural
(1) by precipitation with ammonia (furfuramide), (2) by volumetric
estimation with standardised phenylhydrazine, (3) by weighing the
hydrazone.
In 1893 (Chem. Ztg. 17, 1745) Hotter described a method of quantitative
condensation with pyrogallol requiring a temperature of 100°-110° for
two hours. The insoluble product collected, washed, dried at 103°, and
weighed, gives a weight of 1.974 grm. per 1 grm. furfural.
Councler substitutes phloroglucinol for pyrogallol, with the advantage
of doing away with the digestion at high temperature. (_Ibid._ 18, 966.)
This process, requiring the presence of strong HCl, has the advantage of
being applied directly to the acid distillate, in which form furfural is
obtained as a product of condensation of pentoses, &c. A comparative
investigation was made, precipitating furfural (a) as hydrazone in
presence of acetic acid, and (b) as phloroglucide in presence of HCl
(12 p.ct). In (a) by varying the weights of known quantities of
furfural, and using the factor, hydrazone × 0.516 [+ 0.0104] in
calculating from the weights of precipitates obtained, the maximum
variations from the theoretical number were +1.71 and -1.74. In (b) it
was found necessary to vary the factor from 0.52 to 0.55 in calculating
from phloroglucide to furfural. The greatest _total_ range of variation
was found to be 2.5 p.ct. The phenol process is therefore equally
accurate, has the advantages above noted, and, in addition, is less
liable to error from the pressure in the distillates obtained from
vegetable substances of volatile products, e.g. ketonic compounds,
accompanying the furfural.
This method has been criticised by Helbel and Zeisel [Sitz.-ber, Wiener
Akad. 1895, 104, ii. p. 335] on two grounds of error, viz. (1) the
presence of diresorcinol in all ordinary preparations of phloroglucinol,
and (2) changes in weight of the precipitate of phloroglucide on drying.
The process was carried out comparatively with ordinary preparations,
and with specially pure preparations of the phenol. The quantitative
results were identical. The criticisms in question are therefore
dismissed. Although the process is to be recommended for its simplicity
and the satisfactory concordance of results it is to be noted that it
rests upon an empirical basis, since the phloroglucide is not formed by
the simple reaction 2 [C_{5}H_{4}O_{2} + C_{6}H_{6}O_{3}] - H_{2}O =
C_{22}H_{18}O_{9}, but appears to have the composition
C_{16}H_{12}O_{6}.
In part ii. of this paper the author discusses the question of the
probable extent in the sense of diversity of constitution of
furfural-yielding constituents of plant-tissues. Glucoson was isolated
from glucosazon, and found to yield 2.9-3.6 p.ct. furfural. Gluconic
acid distilled with hydrochloric acid gave traces of furfural; so also
with sulphuric acid and manganic oxide.
Starch was oxidised with permanganate, and a mixture of products
obtained of which one gave a characteristic violet colouration with
phloroglucol, with an absorption-band at the D line. On distilling with
HCl furfural was obtained in some quantity. The product in question was
found to be very sensitive to the action of bases, and was destroyed by
the incidental operation of neutralising the mixture of oxidised
products with calcium carbonate. It was found impossible to isolate the
compound.
UNTERSUCHUNGEN UEBER DIE PENTOSANBESTIMMUNG MITTELST DER
SALZSÄURE-PHLORO-GLUCIN-METHODE.[8]
E. KRÖBER (Journ. f. Landwirthschaft, 1901, 357).
~INVESTIGATION OF THE HYDROCHLORIC ACID-PHLOROGLUCINOL METHOD OF
DETERMINING PENTOSANES.~
This paper is the most complete investigation yet published of the now
well-known method of precipitating and estimating furfural in acid
solution by means of the trihydric phenol. In the last section of the
paper is contained the most important result, the proof that the
insoluble phloroglucide is formed according to the reaction
C_{5}H_{4}O_{2} + C_{6}H_{6}O_{3} - 2H_{2}O = C_{11}H_{6}O_{3},
also, by varying the proportions of the pure reagents interacting, that
the condensation takes place invariably according to this equation.
Incidentally the following points were also established:--The solubility
of the phloroglucide, under the conditions of finally separating in a
condition for drying and weighing, is 1 mgr. per 100 c.c. of total
solution, made up of the original acid solution, in which the
precipitation takes place, and the wash-water required to purify from
the acid. The phloroglucide is hygroscopic, and must be weighed out of
contact with the air. The presence of diresorcinol is without influence
on the result, provided a sufficient excess of actual phloroglucinol is
employed. Thus even with a preparation containing 30 p.ct. of its weight
of diresorcinol the influence of the latter is eliminated, provided a
weight be taken equal to twice that of the furfural to be precipitated.
The phenol must be perfectly dissolved by warming with dilute HCl (1.06
sp.gr.) before adding to the furfural solution. For collecting the
precipitate of phloroglucide the author employs the Gooch crucible.
The paper contains a large number of quantitative results in proof of
the various points established, and concludes with elaborate tables,
giving the equivalents in the known pentoses and their anhydrides for
any given weight of phloroglucide from 0.050 to 0.300 grm.
UEBER DEN PENTOSAN-GEHALT VERSCHIEDENER MATERIALIEN.
B. TOLLENS and H. GLAUBITZ (J. für Landwirthschaft, 1897, 97).
~ON THE PENTOSANE CONSTITUENTS OF FODDER-PLANTS AND MALT.~
(p. 171) (a) The authors have re-determined the yield of furfural from
a large range of plant-products, using the phloroglucol method. The
numbers approximate closely to those obtained by the hydrazone method.
The following may be cited as typical:
Substance Furfural p.ct.
Rye (Göttingen) 6.03
Wheat (square head) 4.75
Barley (peacock) 4.33
Oats (Göttingen) 7.72
Maize (American) 3.17
Meadow hay 11.63
Bran (wheat) 13.06
Malt 6.07
Malt-sprouts 8.56
Sugar-beet (exhausted) 14.95
(b) A comparison of wheat with wheat bran, &c. was made by grinding in
a mortar and 'bolting' the flour through a fine silk sieve. The results
showed:
Furfural p.ct.
Original wheat 4.75
Fine flour 1.73
Bran (24 p.ct. of wheat) 11.25
Wheat-bran of commerce 13.06
It is evident that the pentosanes of wheat are localised in the more
resistant tissues of the grain.
(c) An investigation of the products obtained in the analytical
process for 'crude fibre' gave the following:
(1) In the case of brewers' grains:
100 grms. grains gave furfural = 29.43 pentosane
---------------
20 " crude fibre " = 2.52
Acid extract " = 22.76
Alkali " " = 1.20
Deficiency from total of original grains 2.95
-----
29.43
(2) In the case of meadow hay:
The crude fibre (30 p.ct.) obtained retained about one fourth (23.63
p.ct.) of the total original pentosanes.
(d) An investigation of barley-malt, malt-extract or wort, and
finished beer showed the following: An increase of furfuroids in the
process of malting, 100 pts. barley with 7.97 of 'pentosane' yielding 82
of malt with 11.18 p.ct. 'pentosane'; confirming the observations of
Cross and Bevan (Ber. 28, 2604). Of the total furfuroids of malt about
1/4 are dissolved in the mashing process. In a fermentation for lager
beer it was found that about /10 of the total furfuroids of the malt
finally survive in the beer; the yield of furfural being 2.92 p.ct. of
the 'total solids' of the beer. In a 'Schlempe' or 'pot ale,' from a
distillery using to 1 part malt 4 parts raw grain (rye), yield of
furfural was 9 p.ct. of the total solids.
In a general review of the relationships of this group of plant-products
it is pointed out that they are largely digested by animals, and
probably have an equal 'assimilation' value to starch. They resist
alcoholic fermentation, and must consequently be taken into account as
constituents of beers and wines.
UEBER DAS VERHALTEN DER PENTOSANE DER SAMEN BEIM KEIMEN.[9]
A. SCHÖNE and B. TOLLENS (Jour. f. Landwirthschaft, 1901, 349).
~BEHAVIOUR OF PENTOSANES OF SEEDS IN GERMINATION.~
The authors have investigated the germination of barley, wheat, and
peas, in absence of light, and generally with exclusion of assimilating
activity, to determine whether the oxidation with attendant loss of
weight, which is the main chemical feature of the germination proper,
affects the pentosanes of the seeds. The following are typical of the
quantitative results obtained, which are stated in absolute weights, and
not percentages.
_____________________________________________________________
| | | | |
| | Original seed | Malt or | Pentosane in |
| | | germinated product | |
| | | |_______________|
| | | | | |
| | A | B | A | B |
|________|_______________|____________________|_______|_______|
| | | | | |
| Barley | 500.00 | 434.88 | 39.58 | 40.38 |
| " | 500.00 | 442.26 | 40.52 | 41.17 |
| Peas | 300.00 | 286.60 | 15.25 | 15.97 |
|________|_______________|____________________|_______|_______|
The authors conclude generally that there is a slight absolute increase
in the pentosanes, and that the pentosanes do not belong to those
reserve materials which undergo destructive oxidation during
germination.
In this they confirm the previously published results of De Chalmot,
Cross and Bevan, and Gotze and Pfeiffer.
UEBER DEN GEHALT DER BAUMWOLLE AN PENTOSAN.
H. SURINGAR and B. TOLLENS (Ztschr. angew. Chem., 1897, I).
~PENTOSANE CONSTITUENTS OF COTTON.~
(p. 290) It has been stated by Link and Voswinkel (Pharm. Centralhalle,
1893, 253), that raw cotton yields 'wood gum' as a product of
hydrolysis. The authors were unable to obtain any pentoses as products
of acid hydrolysis of raw cotton, and traces only of furfural-yielding
carbohydrates. They conclude that raw cotton contains no appreciable
quantity of pentosane.
FOOTNOTES:
[8] This paper appears during the printing of the author's original MS.
[9] This paper appears during the printing of the author's original MS.
SECTION VI. THE LIGNOCELLULOSES
(p. 131) ~Lignocellulose Esters.~--By a fuller study of the ester
reactions of the normal celluloses we have been able to throw some light
on the constitutional problems involved; and we have extended the
investigations to the jute fibre as a type of the lignocelluloses, from
the results of which we get a clearer idea of the relationships of the
constituent groups.
Taking the empirical expression for the complex, i.e. the entire
lignocellulose, the formula C_{12}H_{18}O_{9}, we shall be able to
compare the ester derivatives with those of the celluloses, which we
have also referred to a C_{12} unit. But we shall require also to deal
with the constituent groups of the complex, which for the purposes of
this discussion may be regarded as (a) a cellulose of normal
characteristics--cellulose alpha; (b) a cellulose yielding furfural on
boiling with condensing acids--cellulose beta; and (c) a much
condensed, and in part benzenoid, group which we may continue to term
the lig_none_ group.
The latter has been specially examined with regard to its proportion of
OH groups, as a necessary preliminary to the investigation of esters, in
producing which the entire complex is employed. It will be shown that
the ester groups can be actually localised in various ways, as in the
main entering the cellulose residues alpha and beta. But that the
lignone group takes little part in the reactions may be generally
concluded on the evidence of its non-reactivity as an isolated
derivative, (1) By chlorination, &c. it is isolated in the form of an
amorphous body, but of constant composition, represented by the formula
C_{19}H_{18}Cl_{4}O_{9}. This compound, soluble in acetic anhydride, was
boiled with it for six hours after adding fused sodium acetate, and the
product separated by pouring into water. The dilute acid filtered from
the product contained no hydrochloric acid nor by-products of action.
The product showed an increase of weight of 7.5 p.ct. For one acetyl per
1 mol. C_{19}H_{18}Cl_{4}O the calculated increase is 8.0 p.ct. It is
evident from the nature of the derivative that this result cannot be
further verified by the usual analytical methods. (2) The chlorinated
derivative is entirely soluble in sodium sulphite solution. This
solution, shaken with benzoyl chloride, with addition of sodium hydrate
in successive portions, shows only a small formation of insoluble
benzoate, which separates as a tarry precipitate. (3) The empirical
formula of the lignone complex in its isolated forms indicates that very
little hydrolysis occurs in the processes of isolation. Thus the
chlorinated product we may assume to be derived from the complex
C_{19}H_{22}O_{9}. In the soluble by-products from the bisulphite
processes of pulping wood the lignone exists as a sulphonated
derivative, C_{24}H_{23}(OCH_{3})_{2}.(SO_{3}H).O_{7}. The original
lignone may be regarded as passing into solution as a still condensed
complex derived from C_{24}H_{26}O_{12} (Tollens). There is evidently
little attendant hydroxylation, and another essential feature is the
small molecular proportion of groups showing the typical sulphonation.
It appears that in the lignone the elements are approximately in the
relation C_{6} : H_{6} : O_{3}, and it may assist this discussion to
formulate the main constitutional types consistent with this ratio,
viz.:
(1) The trihydroxybenzenes C_{6}H_{3}(OH)_{3}.
(2) Methylhydroxyfurfural C_{5}H_{2}O.(OH)(CH_{3}).
(CH_{3})
/ \
(3) Methylhydroxypyrone CO
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