Chapter 13

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.

ÜBER DIE URSACHE DER VON SIMONSEN BEOBACHTETEN UNVOLLSTÄNDIGKEIT DER VERGÄHRUNG DER AUS HOLZ BEREITETEN ZUCKERFLÜSSIGKEITEN.

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., Göttingen, 1892; Klason, _Rep. d. Chem. Ztg._ 1897, 261; Seidel and Hanak, _Mitt. d. Techn. Gew. Mus._ 1897-1898.

SECTION VII. PECTIC GROUP

UNTERSUCHUNGEN ÜBER PECTINSTOFFE.

R. W. TROMP DE HAAS and B. TOLLENS (Lieb. Ann., 286, 278).

ÜBER DIE CONSTITUTION DER PECTINSTOFFE, B. TOLLENS (ibid. 292).

~INVESTIGATIONS OF PECTINS.~

(p. 216) It is generally held that the pectins are, or contain, oxidised derivatives of the carbohydrates. The authors have isolated and analysed a series of these products, and the results fail to confirm a high ratio O : H. The following are the analytical numbers:

________________________________________________ | | | | | | | Pectin from | Ash | C | H | Ratio H : O | |______________|______|______|_____|_____________| | | | | | | | Apple | 6.2 | 43.4 | 6.4 | 1 : 7.9 | | Cherry | 20.5 | 42.5 | 6.5 | 1 : 7.9 | | Rhubarb | 4.2 | 43.3 | 6.8 | 1 : 7.4 | | Currant | 5.0 | 47.1 | 5.9 | 1 : 8.5 | | Greengage | 3.3 | 43.0 | 5.9 | 1 : 8.5 | | Turnip | 7.3 | 41.0 | 5.9 | 1 : 9.0 | |______________|______|______|_____|_____________|

Acid hydrolysis (4 p.ct. H_{2}SO_{4}) gave syrupy products not crystallisable--in certain cases the hydrolysis was accompanied by separation of insoluble cellulose. The insoluble product from currant pectin had the composition C 54.4, H 5.0.

Tollens points out that the results of empirical analysis are inconclusive; and that from the acid reactions of these products and their combination with bases, carboxylic groups are present, though probably in anhydride or ester form.

The pectins may be regarded as closely related to the mucilages (_Pflanzenschleim_), differing from them only by the presence of the oxidised groups in question.

UEBER DIE CONSTITUTION DER PECTINSTOFFE.

C. F. CROSS (Berl. Ber., 1895, 2609).

~CONSTITUTION OF PECTINS.~

It is pointed out that the composition of the pectin of white currants, as given in the preceding paper, is that of the typical lignocellulose, the jute fibre. The product was isolated and further investigated by the author. It gave 9.8 p.ct. furfural on boiling with HCl (1.06 s.g.), reacted freely with chlorine, giving quinone chlorides, and with ferric ferricyanide to form Prussian blue. This 'pectin' is therefore a form of soluble lignocellulose. The 'pectic' group consequently must be extended to include hydrated and soluble forms of the mixed complex of condensed and unsaturated groups with normal carbohydrates, such as constitute the fibrous lignocelluloses.

UEBER DAS PFLANZLICHE AMYLOID.

E. WINTERSTEIN (Ztschr. Physiol. Chem., 1892, 353).

~ON VEGETABLE AMYLOID.~

(p. 224) A group of constituents of many seeds, distinguished by giving slimy or ropy 'solutions' under the action of boiling water are designated 'amyloid.' They are reserve materials, and in this, as in the physical properties of their 'solutions,' they are very similar to starch. They are, however, not affected by diastase; and generally are more resistant to hydrolysis. Typical amyloids have been isolated by the author from seeds of _Tropoeolum majus, Poeonia officinalis_, and _Impatiens Balsamina_. The raw material was carefully purified by exhaustive treatment with ether and alcohol, &c.; the amyloid then extracted by boiling with water, and isolated by precipitation with alcohol. Elementary analysis gave the numbers C 43.2, H 6.1. On boiling with 12 p.ct. HCl it gave 15.3 p.ct. furfural; oxidised with nitric acid it yielded 10.4 p.ct. mucic acid. Specimens from the two first-named raw materials gave almost identical numbers.

_Hydrolysis._--On boiling with dilute acids these products are gradually broken down, dissolving without residue. In this respect they are differentiated from the mucilages, which give a residue of cellulose (insoluble). From the solution the author isolated crystalline galactose, but failed to isolate a pentose. Dextrose was also not identified directly.

The tissue residues left after extracting the amyloid constituent, as above described, were subjected to acid hydrolysis. A complex of products was obtained, from which galactose was isolated. A furfural-yielding carbohydrate was also present in some quantity, but could not be isolated. The original seed tissues, therefore, contain an amyloid and a hemicellulose, the latter differentiated in its resistance to water. Both yield, however, to acid hydrolysis a complex of products of similar composition and constitution.

UEBER DEN GEHALT DES TORFES AN PENTOSANEN ODER FURFUROLGEBENDEN STOFFEN UND AN ANDEREN KOHLENHYDRATEN.

H. V. FEILITZEN and B. TOLLENS (Berl. Ber., 1897, 2,571).

~CARBOHYDRATE CONSTITUENTS OF PEAT.~

(p. 240) An investigation of typical peats taken at successive depths showed increasing percentage of carbon, and inversely a decreasing yield of furfural. The numbers may be compared with those for _Sphagnum cuspidatum_--with C = 49.80 p.ct., and furfural 7.99 p.ct., calculated to dry, ash-free substance:

__________________________________________________ | | | | | Depth at which taken | C p.ct. | Furfural p.ct. | |_______________________|_________|________________| | _ | | | | | 20-100 cm. | 51.08 | 6.93 | | I. | 100-200 " | 53.52 | 5.30 | | |_ 200-300 " | 58.66 | 3.19 | | _ | | | | | Surface-20 " | 55.47 | 3.40 | | II. | 20-60 " | 55.06 | 3.48 | | | 60-100 " | 58.25 | 1.45 | | | 100-120 " | 58.23 | 1.19 | | |_ 180-200 " | 57.57 | 1.80 | |_______________________|_________|________________|

_Cellulose_ was estimated by the Lange method. The yield from _Sphagnum_ was 21.1 p.ct.

From specimen I. at { 20-100 cm. 15.20 { 100-200 " 6.87

From the peat of lower depths no cellulose could be obtained.

_Hydrolysis_ (acid).--On heating with 1 p.ct. H_{2}SO_{4} at 130-135°, soluble carbohydrates were obtained, amongst which mannose was identified, and galactose shown to be present in some quantity. After fermenting away the hexoses, the residue was treated with phenylhydrazine and an osazone separated. It contained 17.3 p.ct. N, but melted at 130°. The substance could not be identified as an osazone of any of the yet known pentoses.

SECTION VIII. INDUSTRIAL AND TECHNICAL. GENERAL REVIEW

~The Industrial Uses of Cellulose.~

C. F. CROSS (Cantor Lectures, Soc. of Arts, 1897).

(p. 273) A series of three lectures, in which the more important industries in cellulose and its derivatives are dealt with on their scientific foundations, and by means of a selection of typical problems. In reference to textiles, the small number of vegetable fibres actually available, out of the endless variety afforded by the plant world, is referred to the number of conditions required to be fulfilled by the individual fibre, thus: yield per cent. of harvested weight or per unit of field area, ease of extraction, the absolute dimensions of the spinning unit, and the proportion of variation from the mean dimensions; the relative facility with which the unit fibre can be isolated preparatory to the final twisting operation; the chemical constants of the fibre substance, especially the percentage of cellulose and degree of resistance to hydrolysis. It is suggested that any important addition to the very limited number fulfilling the conditions, or any great improvement in these, can only result from very elaborate artificial selection and cultural developments on this basis.

The paper making fibres are shown to fall into a scheme of classification based on chemical constitution, and consisting of the four groups: (a) Cotton [flax, hemp, rhea], (b) wood celluloses, (c) esparto, straw, and (d) lignocelluloses. Papers being exposed to the natural disintegrating agencies, more especially oxygen, water (and hydrolysing agents generally), and micro-organisms, the relative resistance of the above groups of raw materials is discussed as an important condition of value. The indirect influence of the ordinary sizing and 'filling' materials is discussed. The paper-making quality of the fibrous raw materials is also discussed, not merely from the point of view of the form and dimensions of the ultimate fibres, but their capacity for 'colloidal hydration.' This is complementary to the action of rosin, i.e. resin acids, in the engine-sizing of papers; and the proof of the potency of this factor is seen in the superior effects obtained in sizing jointly with solutions of cellulose and, more particularly, viscose and rosin. Wurster's much-cited monograph of the subject of rosin-sizing ['Le Collage des Papiers,' Bull. Mulhouse, 1878] neglects to take into consideration the contribution of the cellulose hydrates to the total and complex sizing effect, and hence gives a partial view only of the function of the resin acids.

In further illustration of fundamental principles various developments in the textile industries are discussed, e.g. the bleaching of jute, cotton, and flax, and special developments in the spinning of rhea and flax.

The concluding lecture deals with later progress in the industrial applications of cellulose derivatives, chiefly the sulphocarbonate (viscose); the nitrates, in their applications to explosives, on the one hand, and the spinning of artificial fibres (lustra-cellulose), on the other; and the cellulose acetates.

~La Viscose et le Viscoide.~

C. H. BARDY (Bull. Soc. d'Enc. Ind. Nationale, 1900, March).

This is a report presented to the Committee of Economic Arts of the above Society, dealing with the industrial progress in products obtained by means of the sulphocarbonate of cellulose (viscose).

The following developments are noted:

_Engine-sized Papers._--The viscose, by coating the fibres with regenerated cellulose hydrate, adds very much to the tensile strength of papers. Increase of 40-60 p.ct. is attainable by addition of cellulose in this form from 1-4 p.ct. on the weight of the paper.

_Viscoid._--Solid aggregates are formed by incorporating viscose with mineral matters, hydrocarbons, &c. Products are cast or moulded into convenient forms, and, after purification and sufficient ageing, are available for various structural uses.

_Paint._--The viscose is used as a vehicle for pigments, the mixture being used either as a paint or for coating papers with fine surfaces, such as required in the reproduction of photo-blocks. In these applications the extraordinary viscosity of the product conditions the economic use of the cellulose in competition with oils, on the one hand, and organic colloids, such as gelatine, casein, &c., on the other.

By suitable alteration of the formula for making the paint a product is obtained which has an extraordinary power of removing paint from old painted surfaces. The product has been officially adopted by the French Admiralty, and receives extensive application in removing the paint from ships.

_Films._--Films are produced from the viscose itself in various ways. Plane or flat by solidifying the viscose on glass surfaces, removing the by-products and rolling the films. The film is also produced by applying the viscose on textile fabrics, drying down, and fixing on a stenter machine, then washing away the alkaline by-products from the fixed film. A large number of industrial effects are obtained by suitably varying the mixtures applied.

_Cellulose-indiarubber._--The viscose, in its concentrated form, can be incorporated with rubber-hydrocarbon mixtures, and these mixtures can be used both as water-proofing films, as applied to textiles, or can be solidified into the class of goods known as 'mechanicals.' The cellulose not only cheapens the mixture, but produces new technical effects.

_Spinning._--The viscose is spun by special methods, patented by C. H. Stearn. As produced in thread form, the diameters are approximately those of natural silk. In commercial form it is a multiple thread (of 15 or more units) at from 50-200 deniers on the silk counts. It is a thread of high lustre, and more nearly approaches the normal cellulose in chemical properties than any of the other artificial silks. It can also be spun in threads of very much larger diameter, which can be used as a substitute for horsehair, for carbonising for incandescent electric lamps, &c.

_Cellulose Esters._--These are conveniently made from cellulose, regenerated from the solution as sulphocarbonate. The tetracetate is made from this product on the industrial scale. Nitrates are conveniently made by treatment with the ordinary mixed acids. For fuller details the original report may be consulted.

VISKOS.

R. W. STREHLENERT (Svensk Kemisk Tidskrift, Stockholm, 1900, p. 185).

A report on the industrial development of viscose, covering essentially the same ground as the above.

~Ueber die Viscose.~

B. M. MARGOSCHES (Reprint from Zeitschrift für die gesammte Textil-Industrie, 1900-01, Nos. 14-20).[11]

~Report of Committee on the Deterioration of Paper.~