(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<C_{4}H_{2} O
\ /
(OH)
__________________
| |
(4) Trioxycyclohexane CH--CH--CH--CH--CH--CH
\ / \ / \ /
O O O
It is probable that all these types of condensation are represented in
the lignone molecules, since the derivatives yielded in decompositions
of more or less regulated character are either directly derived from or
related to such groups. For the moment we pass over all but the general
fact of complexity and the marked paucity of OH-groups. It would be of
importance to be able to formulate the exact mode of union of the
lignone with the cellulose residues to constitute the lignocellulose.
The evidence, however, does not carry us farther than the probability of
union by complicated groups and of large dimensions; for not only is the
lignone isolated in condensed and non-hydroxylated forms, but the
cellulose also is not hydrated or hydrolysed further than in the ratio
3C_{6}H_{10}O_{5}.H_{2}O. It is probable, therefore, that the water
combining with the residues at the moment of their resolution is
relatively small.
Lastly, we have to remember, when dealing with the statistical results
of the reactions to be described, that the approximate proportions per
cent. of the constituent groups are:
Cellulose alpha 65
" beta 15 = 100 lignocellulose.
Lignone 20
~Jute Benzoates.~--In preparing the jute for treatment it was boiled in
alkaline solution (1 per cent. NaOH), washed with water and dilute acid,
again washed, dried, and weighed.
In the ester reaction the reagents were employed in the proportion
C_{12}H_{18}O_{9} : 3NaOH : 2C_{6}H_{5}COCl. A series of quantitative
experiments gave yields of 126-130 p.ct. of benzoate [calculated for
monobenzoate 134 p.ct.].
The results were confirmed by ultimate analysis. The monobenzoate
therefore represents a maximum, and this molecular proportion is
one-half of that observed with the normal cellulose, calculated to the
same unit.
_Localisation of Benzoyl Group._--The entrance of the ester group
affects the typical colour reactions of the lignocellulose, which are
fainter. The ferric ferricyanide reaction almost disappears. The lignone
group is unaffected, and combines with chlorine as in the original. The
lignone chloride is removed by sodium sulphite solution, and the residue
is a _cellulose benzoate_. The loss of weight due to the elimination of
the lignone was 12.7 p.ct. Calculating per 100 of the original
lignocellulose this becomes 16. These statistics further confirm the
localisation of the benzoyl group in the cellulose residue. It is to be
noted that the presence of the benzoyl group renders the cellulose more
resistant to hydrolytic actions. Thus, to bring out this fact more
prominently, we may calculate the yield of residual cellulose benzoate
p.ct. of original jute, and we find it 109 p.ct. Taking a maximum
proportion for original cellulose--viz. 85--this benzoate represents a
yield of 129 p.ct., as against the theoretical for a monobenzoate, 132
p.ct.
_Furfural Numbers._--The percentage of furfural obtained by boiling with
HCl of 1.06 sp.gr. was 3.02 and 3.29 in separate determinations.
Calculating to the original lignocellulose, the percentage, 4.21,
indicates a considerable loss of the furfural-yielding constituent. The
effect was also apparent in the cellulose (benzoate) isolated by
chlorination &c., the percentage being 1.39 p.ct., and calculated to the
original jute benzoate 1.59 p.ct. Under the conditions adopted in
dissolving away the chlorinated lignone the original non-benzoated
lignocellulose would have yielded a cellulose giving 6 to 7 p.ct.
furfural.
Since the benzoyl group is hardly calculated to produce a constitutional
change affecting the furfural constants, it was necessary to examine the
effect of the preliminary alkaline treatment, and the change in the
furfuroid group was in fact localised in this reaction. It was found
that, on washing the alkali from the mercerised jute, and further
purifying the residue, this latter yielded only 4.2 p.ct. furfural [3.4
p.ct. on original fibre]. The alkaline solution and washings were
acidified and distilled from 10 p.ct. HCl, yielding an additional 3.6
p.ct. calculated to the original lignocellulose. By treatment with the
concentrated alkali, therefore, the furfuroid of the original
lignocellulose undergoes little change, but is selectively dissolved.
This point is under further investigation.
(p. 132) ~Acetylation of Lignocelluloses.~--Acetates are readily formed by
boiling the lignocelluloses with acetic anhydride. The derivatives
obtained from jute are only generally mentioned in the 1st edition (p.
132). A further study of the reactions in regard to special points has
led to some more definite results. The _yields_ of product by the
ordinary and simple process are 114-115 p.ct. But on analysing the
product an important discrepancy is revealed.
For the saponification we employ a solution of sodium ethylate in the
cold. The following numbers were obtained:
Acetic acid Hydrocellulose residue
27.2 77.8
Calc. for diacetate on C_{12}H_{18}O_{9} 30.8 78.4
The derivative is approximately a diacetate, and on the assumption of a
simple ester reaction the yield should be 127 p.ct. Assuming that the
difference of 13 p.ct. is due to loss of water by internal condensation,
it appears that for each acetyl group entering, 2 mol. H_{2}O are split
off.
The jute acetate showed the normal reaction with chlorine, and the
lignone chloride was dissolved by treatment with sodium sulphite
solution. The fibrous residue was colourless. It proved to be a
cellulose acetate. The following numbers were obtained on
saponification:
Acetic acid Cellulose
31.6 70.0
30.9 68.8
Calc. for diacetate on C_{12}H_{20}O_{10} 29.4 79.9
The interpretation of these numbers appears to be this: in the original
reaction with the lignocellulose it is the cellulose residue which is
acetylated, and at the same time condensed. The cellulose residue which
undergoes condensation is not of the normal constitution, since the
normal cellulose is acetylated without condensation (see p. 41). On
saponification a portion of the cellulose, in again combining with
water, is hydrolysed to soluble products. The lignone group as it exists
in the lignocellulose has no free OH groups, and probably no free
aldehydic groups such as would react with the anhydride. Such groups
may, however, be originally present, and may take part in the internal
condensations which have been shown to occur. The furfural constants of
the lignocellulose are unaffected by the acetylation and condensation.
The hygroscopic moisture of the product is lowered from 10-11 p.ct. in
the original to 4.5 p.ct. The ferric ferricyanide reaction is inhibited
by the disappearance of the reactive groups, upon which this curious and
characteristic phenomenon depends (1st ed.).
~Acetylation of Benzoates.~--The cellulose dibenzoate (C_{12} basis) and
the jute monobenzoate were acetylated under comparative conditions The
results were as follows:
C_{12} basis
Cellulose dibenzoate Jute monobenzoate
Calc. for Calc. for
Found diacetate on Found diacetate on
Ester reaction dibenzoate monobenzoate
Yield 111 p.ct. 115 p.ct. 124 p.ct. 120 p.ct.
Saponification {Cellulose}
{Lignocellulose} 53.5 52.6 59.8 61.9
NaOH combining 21.3 23.9 28.4 24.3
From these results it would appear that the number of acetyl groups
entering the benzoates is the same as with the unbenzoylated fibres, the
benzoyl has no influence upon the hydroxyls as against the acetyl. At
the same time the internal condensation noticed in the acetylation of
the jute appears not to occur in the case of the benzoate.
~Nitric Esters.~--The numbers resulting from the quantitative study of the
ester reaction and product (1st ed. p. 133) show a very large divergence
of the yield of product from that which would be calculated from its
composition (N p.ct.) on the assumption that the ester reaction is
simple. We have repeated the results, and find with a yield of 145 p.ct.
that the product contains 11.8 p.ct. N.
The reaction
C_{12}H_{18}O_{9} + 4HNO_{3} - 4H_{2}O
gives a tetranitrate with 11.5 p.ct. N and a yield of 159 p.ct. The
ester reaction, therefore, is not simple. There are two sources of the
loss of weight. The first of these is evident from the occurrence of
certain secondary reactions which result in the solution of a certain
proportion of the fibre substance in the acid mixture. To determine this
quantitatively we have devised a suitable variation of the method of
combustion with chromic acid (1st ed.).
The variation is required to meet the difficulty occasioned by the
tension of the nitric acid and products of deoxidation. The mixed acids
(10 c.c.), containing the organic by-products in solution, are
carefully diluted in a small flask with an equal volume of water,
preventing rise of temperature. Nitrous fumes are evolved during the
dilution. Strong sulphuric acid (15 c.c.) is now added, and the residue
of nitrous fumes expelled by a current of air, agitating the contents of
the flask from time to time. The combustion with CrO_{3} is then
proceeded with in the ordinary way. The gases evolved are measured
(total volume) and calculated to C present in the form of products
derived from the lignocellulose; and, assuming that this contains 47
p.ct. C, we may express the result approximately in terms of the fibre
substance. The method was controlled by blank experiments, in which
citric acid was taken as a convenient carbon compound for combustion.
The C found was 34.9 p.ct. as against 34.3 p.ct. calculated. By this
method we find that with maximum yields of nitrate at 143-145 p.ct. the
organic matter in solution in the acid mixture amounted to 4.9 to 5.3
p.ct. of the original lignocellulose.
Introducing this quantity as a correction of the yield of nitrate in the
original reaction, we must express the 143 parts as obtained from 95 of
fibre substance instead of 100.
The yield per molecule C_{12}H_{18}O_{9} (= 306) is therefore 462,
whereas for a tetranitrate formed by a simple ester reaction the yield
should be 486. The difference (24) represents 1.5 mol. H_{2}O split off
by internal condensation.
The correction for total N is relatively small, raising it from 11.5 to
12.2, which remains in close agreement with the experimental numbers.
_Monobenzoate._--Treated with the acid mixture yields a mixed nitrate.
The yield is 130 p.ct., and the product contains 7.6 p.ct. O.NO_{2}
nitrogen. These numbers approximate to those required for reaction with
4HNO_{3} groups, three of the residues entering the cellulose, and one
(as NO_{2}) the benzene ring of the substituting group. For such a
reaction the calculated numbers are: Yield 144 p.ct.; O.NO_{2} nitrogen
7.1 p.ct.
The experimental numbers require correcting for the amount of loss in
the form of products soluble in the acid mixture, viz. 7.6 p.ct.; but
they remain within the range of the experimental errors sufficiently to
show that the benzoyl group limits the number of OH groups taking part
in the ester reaction to three. The corrected yield per 1 mol. of jute
benzoate (410) is 576, as against the calculated 590 for 4HNO_{3}
reacting. A loss of 1H_{2}O per molecule by internal condensation is
therefore indicated.
~Denitration.~--The removal of the nitric groups from the esters is
effected by digestion with ammonium sulphide. But the reactions are by
no means simple. There is considerable hydrolysis of the lignocellulose
to soluble products. Thus the _tetranitrate_ yields only 46.4 of
denitrated fibre in place of the calculated 66. The product is a
cellulose, yielding only 0.5 per cent. furfural. The hydrolysed
by-products, moreover, when freed from sulphur and distilled from
hydrochloric acid, yielded only an additional 2.5 p.ct. furfural,
calculated to the original lignocellulose.
These statistics confirm the evidence that the ester reaction is not
simple. Such changes take place in the lignone-beta-cellulose complex
that they revert, not to their original form, but to soluble derivatives
of different constitution. The mixed nitrate from the benzoate is
denitrated to a cellulose amidobenzoate, which confirms the localisation
of a nitro-group in the benzoyl residue.
(p. 157) ~General Characteristics of the Lignocelluloses.~--Later
investigations have somewhat modified and simplified our views of the
constitution of the typical lignocellulose (jute), so far as this can be
dealt with by the statistics of its more important decompositions
(original, pp. 157-161).
~Cellulose.~--There is little doubt that the furfural-yielding groups of
the original are isolated in the form of the beta-cellulose. Tollens
emphasises this fact in his studies of cellulose-estimation methods. We
had previously shown (original, p. 159) that the yield of furfural is
not affected by the _chlorination_, but it appears from our numbers that
only 50 p.ct. of these groups remain in the isolated cellulose, the
residue undergoing hydrolysis to soluble compounds. In a carefully
regulated hydrolysis following the chlorination it appears that the
furfuroids are almost entirely conserved in the form of a cellulose.
Moreover, an investigation of the products dissolved by sodium sulphite
solution from the chlorinated fibre has shown that they are practically
free from furfuroids. This enables us to exclude the furfural-yielding
groups from the lignone complex. At the same time, through our later
studies of the hydroxyfurfurals, it is certain that these products are
represented in the fibre substance and probably in the lignone complex.
~Chlorination Statistics.~--It has been pointed out by a correspondent--to
whom we express our indebtedness--that we have made a mistake in
calculating the proportion of lignone from the ratio of the Cl combining
with the fibre substance or lignocellulose (p.ct), to that of the Cl
_present in_ the isolated lignone chloride (p.ct.). The lignocellulose
combines with chlorine in the ratio 100 : 8, but the lignone chloride
_containing_ 26.7 of chlorine means that, neglecting the hydrogen
substituted, 73 of lignone combine with the 27 of chlorine
approximately. On the uniform percentage basis the calculated proportion
of lignone would be 8/37, or a little over 20 p.ct.
In regard to the proportion of hydration attending the resolution, we
have shown on constitutional grounds that this must be relatively small.
Assuming approximately the formula C_{19}H_{22}O_{9} for the lignone
residue as it exists in combination, and the anhydride formula for the
cellulose, these revised statistics now appear, as regards the carbon
contents of the lignocellulose:
Cellulose, 44.4 C; lignone, 57.8.
80 x 44.4 / 100 = 35.52
20 x 57.8 / 100 = 11.56
_____
47.08 p.ct. C in lignocellulose.
These conclusions are in accordance with the experimental facts, and,
taken together with the new evidence we have accumulated from a study of
the lignocellulose esters, we may sum up the constitutional points as
follows: The lignocellulose is a complex of
Cellulose alpha Cellulose beta Lignone
65 p.ct. 15 p.ct. 20
Allied to the normal Yielding furfural One-third of which
celluloses approximately 50 p.ct. is of benzenoid
type
The lignone contains but little hydroxyl. The celluloses are in
condensed hydroxyl union with the lignone, but the combination occurs by
complexes of relatively large molecular weight.
DIE CHEMIE DER LIGNOCELLULOSEN--EIN NEUER TYPUS.
W. C. HANCOCK and O. W. DAHL (Berl. Ber., 1895, 1558).
~Chemistry of Lignocelluloses--A New Type.~
The stem of the aquatic _AEschynomene aspera_ offers an exceptional
instance of structural modification to serve the special function of a
'float,' 1 grm. of substance occupying an apparent volume of 40-50 c.c.
This pith-like substance is morphologically a true wood (De Bary), and
the author's investigations now establish that it is in all fundamental
points of chemical composition a lignocellulose, although from its
colour reactions it has been considered by botanists to be a cellulose
tissue containing a proportion of lignified cells. Thus the main tissue
is stained blue by iodine in presence of hydriodic acid (1.5 s.g.), and
the colour is not changed on washing. The ordinary lignocelluloses are
stained a purple brown changed to brown on washing. The reactions with
phloroglucol and with aniline salts, characteristic of these compounds,
is only faintly marked in the main tissue, though strongly in certain
individual cells.
The following quantitative determinations, however, establish the close
similarity of the product to the typical lignocelluloses:
_Elementary Analysis._--C 46.55, H 6.7. _Furfural_ 11.6 p.ct., of which
there remained in the residue from alkaline hydrolysis (71 p.ct.) 8.0,
i.e. about 70 p.ct. The distribution of the furfuroids is therefore not
affected by the alkaline treatment.
_Chlorination._--The substance (after alkaline hydrolysis) takes up 16.9
p.ct. Cl, of which approximately one-half is converted into hydrochloric
acid.
_Methoxyl._--O.CH_{3} estimated = 2.9 p.ct.
_Ferric Ferricyanide Reaction._--Increase of weight due to blue cyanide
fixed (1) 75 p.ct., (2) 96 p.ct. Ratio, Fe : CN = 1 : 2, 4.
_Hydroxyl Reactions._--In the formation of nitric esters and in the
sulphocarbonate reaction the substance gave results similar to those
obtaining for the jute fibre.
These results establish the general identity of this peculiar product of
plant life with the lignocelluloses, at the same time that they show
that certain of the colour reactions supposed to characterise the
lignocelluloses are due to by-products which may or may not be present.
(p. 172) ~Composition of Elder Pith.~--In a systematic investigation of
the celluloses in relation to function we shall have to give special
attention to the parenchymatous tissues of all kinds. These are, for
structural reasons, not easily isolated, for which reason and their
generally 'inferior' functions they do not present themselves to
chemical observation in the same obvious way as do their fibrous
relatives. The pith of the elder, however, _is_ readily obtained in
convenient masses, and a preliminary investigation of the entire tissue
has established the following points:
The _reactions_ of the tissue are in all respects those of the
lignocelluloses.
_Composition._--Ash, 2.2 p.ct.; moisture in air-dry state, 12.3 p.ct.
Alkaline hydrolysis (loss): (a) 14.77, (b) 17.84. Cellulose (yield),
52.33 p.ct. Nitrate-reaction complicated by secondary reactions and
yields low, 90.95 p.ct. _Sulphocarbonate reaction:_ Resists the
treatment, less than 10 p.ct. passes into solution.
_Furfural._--The original tissue yields 7.13 p.ct.; the residue from
alkaline hydrolysis (b) 5.40 p.ct.
This tissue is, therefore, a lignocellulose having the chemical
characteristics typical of the group, but of less resistance to
hydrolytic actions.
The investigation will be prosecuted in reference to the cause of
differentiation in this latter respect. Probably the pectocelluloses are
represented in the tissue.
~The Insoluble Carbohydrates of Wheat (grain).~
H. C. SHERMAN (J. Amer. Chem. Soc., 1897, 291).
(p. 171) This is a study of the constituents of the cell-walls of wheat
grain. Bran was taken as the most convenient form of the raw material,
being freed from starch by treatment with malt extract, and further
treated (1) with cold dilute ammonia, (2) cold dilute soda lye (2 p.ct.
NaOH), and (3) boiling 0.1 p.ct. NaOH. The product retained only 1.25
p.ct. proteids, and yielded 15.62 p.ct. furfural.
_Acid Hydrolysis._--The product was boiled 30 mins. with dilute acid
(1.25 p.ct. H_{2}SO_{4}), and the solution boiled until the Fehling test
showed no further increase of monoses. At the limit the reducing power
of the dissolved carbohydrates was 91.3 p.ct., that of dextrose.
Converted into osazones the analysis showed them to be _pure
pentosazones_. The _hemicellulose_ of wheat is, therefore, according to
the author, _pure pentosane_.
_Residue._--This was a lignocellulose yielding 11.5 p.ct. furfural. It
was subjected to a series of treatments with ferric ferricyanide, and
the proportion of Prussian blue fixed was determined by increase of
weight, viz. from 10 p.ct. to 47 p.ct. according to the conditions. The
results confirmed those of Cross and Bevan first obtained with the
typical lignocellulose (jute).
_Chlorination._-The residue was boiled with dilute alkali, washed, and
exposed to chlorine gas. The resulting lignone chloride was isolated by
solution in alcohol, &c. It yielded 26.7 p.ct. Cl on analysis. In this
and its properties it appeared to be identical with the product isolated
by Cross and Bevan from jute, with the empirical formula
C_{19}H_{18}Cl_{4}O_{9}.
_Cellulose_ was isolated from the residue by three of the well-known
methods, and the following comparative numbers are noteworthy:
_________________________________________________________________________
| | | | |
| | F. Schulze | Lange | Cross and |
| Method | Dil. HNO_{3} | Fusion KOH | Bevan |
| | KClO_{3} | | Chlorine, &c. |
|_____________________________|______________|____________|_______________|
| | | | |
| Cellulose p.ct. obtained | 66.0 | 39.3-43.1 | 66.5 |
| Furfural p.ct. of cellulose | 7.0 | 3.96 | 5.62 |
| Residual nitrogen | 0.22 | 0.03 | 0.00 |
| Ferricyanide reaction, | | | |
| Prussian blue fixed | 6.04 | 0.89 | 0.92 |
|_____________________________|______________|____________|_______________|
The author remarks: 'It is evident no one feature can be urged as a
criterion in judging between the methods, but all must be taken into
consideration. Such a comparison shows the superiority of the
chlorination method.'
The cellulose is not of the normal (cotton) type, since on treatment
with sulphuric acid it dissolves with considerable discolouration, but
only to the extent of about 80 per cent. The dissolved monoses converted
into osazones were found to consist of hexoses only. The cellulose
treated with caustic soda solution (5 p.ct. NaOH) in the cold yielded 20
p.ct. of its weight of soluble constituents, but as the residue yielded
3.34 p.ct. furfural the attack of the alkali is by no means confined to
the furfuroids.
~Animal Digestion of the Constituents of Bran.~--Observations on a steer
fed upon wheat bran only established the following percentage digestion
of the several constituents:
Soluble carbohydrates 96.9
Starch 100.0
Free pentosanes 60.2
Cellulose 24.8
Lignin complex 36.7
Proteid 82.96
Ether extract 42.73
_____________________ ______
Nitrogen-free extract 76.08
Crude fibre 32.21
JOURNAL OF THE IMPERIAL INSTITUTE
(Research Department, Vols. 1-2, 1895-6).
(p. 109) In this journal appear a series of notices of the results of
analyses of vegetable fibres by the method described in 'Report on
Miscellaneous Fibres' (Col. Ind. Exhibition Reports, p. 368) [C. F.
Cross]. These investigations deal with the following subjects:
1895. p. 29 Various Indian Fibres--more particularly Sida.
118 (a) Fibres from Victoria; (b) Special Analyses of
(a) Samples of Jute; (c) Paper-making Fibres
from S. Australia.
202 Fibres from Victoria.
287 Fibres from Victoria.
366 Sisal from Trinidad.
373 Rope-fibres from Grenada.
(b) 398 Report of Experiments on Indian Jute (1).
435} Fifth and Sixth Report on Australian Fibres.
473}
1896. 68 Hibiscus and Abroma Fibres.
104-5 Hibiscus, Urena, and Crotalaria Fibres.
141 Indian Sisal
(c) 182-3 Report of Experiments on Indian Jute (2).
264 Sanseviera from Assam.
From the above we may draw the general conclusion that the scheme of
investigation has been found in practice to answer its main purpose,
viz. to afford such numerical constants as determine industrial values.
In illustration we may cite (a) the results of analyses of specially
selected samples of jute, from which it will be seen that there is a
close concordance of value as ordinarily determined from external
appearance, with the chemical constants as determined in the laboratory.
__________________________________________________________________
| | |
| | Quality of Jute |
|____________________________|_____________________________________|
| | | | | |
| | Low | Medium | Extra | Extra Fine |
|____________________________|_______|________|_______|____________|
| | | | | |
| Moisture | 11.0 | 10.4 | 11.1 | 9.6 |
| Ash | 0.87 | 2.8 | 1.0 | 0.7 |
| Alkaline hydrolysis (a) | | | | |
| 5 mins. boiling | 13.2 | 11.6 | 8.5 | 9.1 |
| Alkaline hydrolysis (b) | | | | |
| 60 mins. boiling | 16.1 | 17.5 | 12.5 | 13.1 |
| Mercerising treatment | 9.2 | 10.5 | 10.3 | 8.5 |
| Nitration (increase p.ct.) | 36.6 | 35.7 | 37.5 | 36.7 |
| Cellulose (yield) | 71.4 | 70.0 | 79.0 | 77.7 |
| Acid purification | 2.6 | 1.3 | 1.9 | 2.0 |
|____________________________|_______|________|_______|____________|
A useful series of experiments, initiated by the Institute, is that
noted under (b) and (c) above.
(1) To ascertain the quality of the fibre extracted from the plant at
different stages of growth, quantities of 400 lbs. of the stalks were
cut at successive stages and the fibre isolated after steeping 14-20
days. The fibre was shipped to England and chemically investigated, with
the following results:
No. 1. Cut before appearance of inflorescence.
" 2. " after budding.
" 3. " in flower.
" 4. " after appearance of seed-pod.
" 5. " when fully matured.
_________________________________________________________________
| | | | | | |
| | (1) | (2) | (3) | (4) | (5) |
|___________________________|_______|_______|______|______|_______|
| | | | | | |
| Moisture | 11.55 | 8.74 | 10.7 | 10.0 | 9.72 |
| Ash | 1.1 | 1.1 | 1.1 | 1.1 | 0.90 |
| Alkaline hydrolysis (a) | 6.2 | 8.5 | 9.7 | 8.9 | 7.3 |
| " " (b) | 10.5 | 11.9 | 11.6 | 12.0 | 11.2 |
| Mercerising treatment | 10.2 | 10.7 | 12.0 | 8.1 | 11.0 |
| Nitration | 37.2 | 32.1 | 32.2 | 33.2 | 36.6 |
| Cellulose | 74.0 | 76.2 | 74.1 | 74.8 | 76.4 |
| Acid purification | 0.8 | 0.5 | 0.7 | 2.4 | 1.4 |
|___________________________|_______|_______|______|______|_______|
It will be thus seen that there are no changes of any essential kind in
the chemical composition of the bast fibre throughout the life-history
of the plant, confirming the conclusion that the 'incrustation' view of
lignification is consistent only with the structural features of the
changes, and so far as it has assumed the gradual overlaying of a
cellulose fibre with the lignone substance it is not in accordance with
the facts.
Examination of the samples from the point of view of textile quality
showed a superiority of No. 1 in fineness, softness, and strength; from
this stage there is observed a progressive deterioration, but the No. 4
sample (which was taken at the usual period of cutting) is superior to
No. 5.
In a further series of experiments (c) the jute was subjected to
certain chemical treatments immediately after the separation of the
fibre from the plant. These consisted in steeping (1) in solution of
sodium carbonate, as well as of plant ashes, and (2) in sulphite of
soda, the purpose of the treatments being to modify or arrest the
changes which take place in the fibre when press-packed in bales for
shipment. The samples were shipped from India under the usual conditions
and examined soon after arrival. It was found that the chemical
treatments had produced but small changes in chemical composition of the
fibre-substance. The sulphite treatment was the more marked in
influence, somewhat lowering the cellulose and nitration constants. The
conclusion drawn from the results was that they afford no prospect of
any useful modification, i.e. improvement of the textile quality of the
fibre by any chemical treatments such as could be applied to the fibre
on the spot before drying for press-packing and shipment.
The other matters investigated in the Institute laboratory and reported
on as indicated above are rather of commercial significance, and
contributed no points of moment to the chemistry of cellulose.
OBSERVATIONS ON SOME OF THE CHEMICAL SUBSTANCES IN THE TRUNKS OF TREES.
F. H. STORER (Bull. Bussey Inst., 1897, 386).
(p. 172) An examination of the outer and inner wood and of the bark of
the grey birch, at different seasons of the year, gave the following
yields of furfural p.ct. on the dry substance:
________________________________
| | | |
| | Wood | |
| |_______________| Bark |
| | | | |
| | Inner | Outer | |
|_________|_______|_______|______|
| | | | |
| May | 21.3 | 19.6 | 16.7 |
| July | 16.6 | 18.8 | 11.4 |
| October | 16.2 | 16.3 | 12.3 |
|_________|_______|_______|______|
The paper contains the results of treating the woods and various
vegetable products with hydrolysing agents in order of intensity: (a)
Malt-extract at 60 deg.C., (b) boiling dilute HCl (1.0 p.ct. HCl), and
(c) boiling dilute HCl (2.5 p.ct.). The residues were found to yield
considerable proportions of furfural. The following numbers are typical:
________________________________________________________________________
| | | |
| | Birch | Stones of |
| |_____________|__________________________|
| | | | | | |
| | Bark | Wood | Date | Apricot | Peach |
|_______________________________|______|______|________|_________|_______|
| | | | | | |
| Action of malt extract calcu- | | | | | |
| lated as starch dissolved | 4.24 | 3.5 | 5.2 | 1.5 | -- |
| | | | | | |
| Residue boiled, 1 p.ct. HCl | | | Mannan | | |
| gave pentosanes dissolved. | -- | -- | 11.7 | 14.1 | 6.7 |
| | | | | | |
| Residue yielded furfural | 19.3 | 17.8 | 3.4 | 9.6 | 9.7 |
|_______________________________|______|______|________|_________|_______|
The proportion of pentosanes (furfuroids) removed, i.e. hydrolysed by
boiling with hydrochloric acid of 2.5 p.ct. HCl, is shown by the
following estimations of furfural:
_________________________________________________________________
| | | | |
| | Birch | Sugar maple | |
| |______________|_______________| Apricot |
| | | | | | stones |
| | Bark | Wood | Outer | Inner | |
| | | | wood | wood | |
|________________________|_______|______|_______|_______|_________|
| | | | | | |
| In original substance | 16.7 | 19.6 | 18.2 | 20.7 | 18.4 |
| | | | | | |
| In residue from action | 6.53 | 8.6 | 4.9 | 6.4 | 7.0 |
| of 2.5 p.ct. HCl | | | | | |
|________________________|_______|______|_______|_______|_________|
_Wood Gum._--The paper contains some observations on the various methods
of isolating this product. Attention is directed to the necessary
impurity of the product, and to the fact that the numbers for furfural
and for the xylose yielded by hydrolysis are considerably less than for
a pure pentosane.
_Estimation of Cellulose._--The author investigated the process of Lange
and the 'celluloses' obtained from various raw materials. The products
from the woods of birch and maple contained furfural-yielding
constituents, represented by yields of 6-8 p.ct. furfural. Preference is
given to the process by comparison with others, at the same time that it
is recommended in all cases to examine the product for furfural
quantitatively, converting the numbers into pentosane equivalents, and
subtracting from the total 'cellulose' to give the true cellulose.
ZUR KENNTNISS DER MUTTERSUBSTANZEN DES HOLZGUMMI.
E. WINTERSTEIN (Ztschr. Physiol. Chem., 1892, 381).
~ON THE MOTHER SUBSTANCES OF WOOD-GUM.~
(p. 188) According to the text-books beech-wood may be regarded as the
typical raw material for the preparation of the laboratory product known
as wood-gum. The author has subjected beech-wood and beech-wood
cellulose (Schulze process) to a range of hydrolytic treatments, acid
and alkaline, in order to determine the conditions of selective action
upon the mother substance of the wood-gum. In the main it appears that
this group of furfuroids is equally resistant with the cellulose
constituents of the wood; in fact, that the mother substance of wood-gum
is a modified cellulose, and exists in the wood in chemical combination
with the 'incrusting substances.'
Of the author's experimental results the following may be cited as
typical:
Yield of furfural
Substance p.ct.
Original beech-wood 13.8
After boiling 3 hrs. with 1.25 p.ct. H_{2}SO_{4} (residue) 10.1
" " " " 5.0 " " " 5.6
Cellulose--isolated by Schulze process (yield 53 p.ct.) 6.9
" after further 14 days' digestion with the
Schulze acid (HNO_{3} + KClO_{3}) 5.9
" after extraction with 5 p.ct. NaOH in
cold (residue) 5.0
" after second extraction with 5 p.ct. NaOH
in cold (residue) 4.4
UEBER DIE FRAGE NACH DEM URSPRUNG UNGESAeTTIGER VERBINDUNGEN IN DER
PFLANZE.
C. F. CROSS, E. J. BEVAN, and C. SMITH (Berl. Ber., 1895, 1940).
~ON THE SOURCE OF THE UNSATURATED COMPOUNDS OF THE PLANT.~
(p. 179) In distilling for furfural by the usual methods of boiling
cellulosic products with condensing acids, the furfural is accompanied
by volatile acids, also products of decomposition of the cellulosic
complex. A series of distillations was carried out with dilute sulphuric
acids of varying concentration from 10-50 H_{2}SO_{4} : 90-50 H_{2}O by
weight, using barley straw as a typical cellulosic material. The
distillates were collected in successive fractions, and the furfural and
volatile acid determined. The results are given in the form of curves.
The aggregate yields were as follows:--
Concentration of acid
(H_{2}SO_{4}) p.ct. 10 15 20 30 40 50
Furfural yield p.ct. of straw 2.0 2.0 4.4 10.1 11.5 11.0
Volatile acid (calculated
as acetic acid) p.ct. of straw 1.7 1.9 3.1 4.3 6.3 14.8
With acids up to 20 p.ct. H_{2}SO_{4} both products are formed
concurrently and in nearly equal quantity. With the 30 p.ct. acid there
is a great increase in the total furfural, and with the 40 p.ct. acid it
reaches nearly the maximum obtainable with HCl of 1.06 s.g. (Tollens),
in this case 12.4 p.ct. The volatile acid increases, but in less ratio;
it is also produced concurrently. With 50 p.ct. H_{2}SO_{4} the
conditions are changed. The total furfural is rapidly formed, whereas
the volatile acid continues to be formed long after the aldehyde ceases
to come over. Moreover, whereas in the previous cases it was mainly
acetic acid, it is now mainly formic acid. The method was then extended
to a typical series of celluloses, heated with the more concentrated
acid (40-50 p.ct. H_{2}SO_{4}), with the following results:
__________________________________________________
| | | |
| | | Volatile acid |
| | |_________________|
| | | | |
| | | Acetic | Formic |
|________________________|_______|________|________|
| | | | |
| Swedish filter-paper | 0.3 | 2.7 | 17.2 |
| Esparto cellulose | 12.4 | 3.2 | 16.6 |
| Bleached cotton | trace | 3.1 | 13.2 |
| Raw cotton (American) | -- | 5.0 | 9.4 |
| Jute cellulose | 5.2 | 4.9 | 22.7 |
| Beech (wood) cellulose | 6.4 | 3.5 14.6 |
|________________________|_______|________|________|
The tendency in the hexoses and their polyanhydrides to split off one
carbon atom in the oxidised form, throws some light on the furfurane
type of condensation, which is represented in the lignocelluloses. We
are still without any evidence as to the possible transition of the
hexoses to benzenoid compounds. Such transitions would be more easily
explained on the assumption that the celluloses are composed in part of
polyanhydrides of the ketoses.
SPIRITUS AUS CELLULOSE UND HOLZ.
E. SIMONSEN (Ztschr. angew. Chem., 1898, 3).
~PRODUCTION OF ALCOHOL FROM CELLULOSE AND WOOD.~
(pp. 50, 209) This investigation was undertaken with one main object--to
determine the optimum conditions of treatment of wood-cellulose and of
wood itself for conversion into 'fermentable sugar.' The process of
'inversion' or hydrolysis, by digestion with dilute acid at high
temperature, involves the four main factors: pressure (i.e.
temperature), concentration of acid, ratio of liquid to cellulose and
duration of digestion. Each of these was varied in definite gradations,
and the effect measured. The degree of action was measured in terms of
'reducing sugar,' calculated from the results of estimation by Fehling
solution, as 'glucose' per cent. of original cellulose (or wood).
(a) _Cellulose._ [Wood-cellulose obtained by bisulphite
process.]--With a proportion of total liquid to cellulose of 27 : 1, and
using sulphuric acid as the hydrolysing agent, the optimum results were
obtained with acids of 0.45-0.60 p.ct. (H_{2}SO_{4}) and pressures of
6-8 atm. The maximum yield of 'sugar' was 45 p.ct. of the cellulose.
Under the above conditions the maximum of conversion is attained in 2
hours.
Having now regard to the production of a solution of maximum
_concentration_ of dissolved solids, the following conditions were
asertained to fulfil the requirement, and, in fact, may be regarded as
the economic optimum:
Proportion of total liquid 6 times wt. of cellulose
Concentration of acid 0.5 p.ct. H_{2}SO_{4}
Pressure 10 atm.
Duration of digestion 1.5 hour
giving a yield of 41 p.ct. 'reducing sugar' calculated to the original
cellulose (dry).
_Alcoholic Fermentation of Neutralised Extract._--The liquors were found
to ferment freely, and on distillation to yield a quantity of alcohol
equal to 70 p.ct. of the theoretical--i.e. on the basis of the numbers
for copper oxide reduction.
(b) _Hydrolytic 'Conversion' of Wood (Lignocellulose)._--A similarly
systematic investigation carried out upon pine sawdust established the
following as optimum conditions:
Proportion of total liquid 5 times wt. of wood
Concentration of acid 0.5 p.ct. H_{2}SO_{4}
Pressure 9 atm.
Duration of digestion 15 minutes
giving a yield of 20 p.ct. 'reducing sugar,' calculated from the
'Fehling' test.
_Fermentation_ of the neutralised extracts gave variable results. The
highest yields obtained were 60 p.ct. of theoretical, the author finally
concluding that under properly controlled conditions of inversion and
fermentation 100 kg. wood yield 6.5 l. absolute alcohol.
UeBER DIE URSACHE DER VON SIMONSEN BEOBACHTETEN UNVOLLSTAeNDIGKEIT DER
VERGAeHRUNG DER AUS HOLZ BEREITETEN ZUCKERFLUeSSIGKEITEN.
B. TOLLENS (Ztschr. angew. Chem., 1898, 15).
~ON THE CAUSE OF INCOMPLETE FERMENTATION OF SUGARS OBTAINED BY ACID
HYDROLYSIS OF WOOD.~
The author criticises Simonsen's explanation of the results obtained
with extracts from pine wood. The incompleteness of fermentation of the
products is certainly due in part to the presence of furfural-yielding
carbohydrates, which are resistant to yeast. The pine woods contain 8-10
p.ct. of these constituents in their anhydride form ('pentosanes'). They
yield readily to acid hydrolysis, and certainly constitute a
considerable percentage of the dissolved products. A similar complex was
obtained by the author in his investigation of peat (Berl. Ber. 30,
2571), and was found to be similarly incompletely attacked by yeast. The
yields of alcohol corresponded with the proportion of the total
carbohydrates disappearing. These were the hexose constituents of the
hydrolysed complex, the pentoses (or 'furfuroids') surviving intact.
UEBER SULFITCELLULOSEABLAUGE.
H. SEIDEL (Ztschr. angew. Chem., 1900).
~WASTE LIQUORS FROM BISULPHITE PROCESS.~
(p. 210) Later researches confirm the conclusion that in the soluble
by-products of these cellulose processes the S is combined as a SO_{3}H
group. The following analyses of the isolated lignin sulphonic acid are
cited:
________________________________________________
| | | | |
| | C | H | S |
|__________________________|_______|______|______|
| | | | |
| (a) Lindsey and Tollens | 56.12 | 5.30 | 5.65 |
| (b) Seidel (1) | 56.27 | 5.87 | 5.52 |
| (c) Seidel and Hanak (2) | 53.69 | 5.22 | 8.80 |
| (d) Street | 50.22 | 5.64 | 7.67 |
|__________________________|_______|______|______|
The variations are due to the varying conditions of the digestion of the
wood and to corresponding degrees of sulphonation of the original
lignone group. Calculating the composition of the latter from the above
numbers on the assumption that the S represents SO_{3}H, the following
figures result:
__________________________________
| | | | |
| | (a) and (b) | (c) | (d) |
|___|_____________|_______|_______|
| | | | |
| C | 64.00 | 65.1 | 59.61 |
| H | 6.65 | 6.33 | 6.69 |
|___|_____________|_______|_______|
This author considers that beyond the empirical facts established by the
above named[10] very little is yet known in regard to the constitution
of the lignone complex.
Nor is there any satisfactory application of this by-product as yet
evolved. Evaporation and combustion involve large losses of sulphur
[D.R.P. 74,030, 83,438; Seidel and Hanak, Mitt. Techn. Gew. Mus. 1898].
A more complete regeneration of the sulphur has been the subject of a
series of patents [D.R.P. 40,308, 69,892, 71,942, 78,306, 81,338], but
the processes are inefficient through neglect of the actual state of
combination of the S, viz. as an organic sulphonate. The process of V.B.
Drewson (D.R.P. 67,889) consists in heating with lime under pressure,
yielding calcium monosulphite (with sulphate and the lignone complex in
insoluble form). The sulphite is redissolved as bisulphite by treatment
with sulphurous acid. This process is relatively costly, and yields
necessarily an impure lye. It has been proposed to employ the product as
a foodstuff both in its original form and in the form of benzoate
(D.R.P. 97,935); but its unsuitability is obvious from its composition.
A method of destructive distillation has been patented (D.R.P. 45,951).
The author has investigated the process, and finds that the yield of
useful products is much too low for its economical development. Fusion
with alkaline hydrates for the production of oxalic acid (D.R.P. 52,491)
is also excluded by the low yield of the product.
The application of the liquor for tanning purposes (D.R.P. 72,161)
appears promising from the fact that 28 p.ct. of the dry residue is
removed by digestion with hide powder. This application has been
extensively investigated, but without practical success. Various
probable uses are suggested by the viscosity of the evaporated extract.
As a substitute for glue in joinery work, bookbinding, &c., it has
proved of little value. It is applied to some extent as a binding
material in the manufacture of briquettes, also as a substitute for
gelatin in the petroleum industry. Cross and Bevan (E.P. 1548/1883) and
Mitscherlich (D.R.P. 93,944 and 93,945) precipitate a compound of the
lignone complex and gelatin by adding a solution of the latter to the
liquors. The compound is redissolved in weak alkaline solutions and
employed in this form for engine-sizing papers. Ekman has patented a
process (D.R.P. 81,643) for 'salting out' the lignone sulphonates, the
product being resoluble in water and the solution having some of the
properties of a solution of dextrin. Owing to its active chemical
properties this product--'dextron'--has a limited capability of
substituting dextrin. The suggestion to employ the evaporated extract as
a reducing agent in indigo dyeing and printing has also proved
unfruitful. The author's application of the soda salt of the lignone
sulphonic acid as a reducing agent in chrome-mordanting wool and woollen
goods (D.R.P. 99,682) is more successful in practice, and its industrial
development shows satisfactory progress. The product is known as
'lignorosin.'
FOOTNOTES:
[10] See more particularly: Lindsey and Tollens, _Annalen_, 267, 341;
Cross and Bevan's _Cellulose_, pp. 197-203; Street, Inaug.-Diss.,
Goettingen, 1892; Klason, _Rep. d. Chem. Ztg._ 1897, 261; Seidel and
Hanak, _Mitt. d. Techn. Gew. Mus._ 1897-1898.