Part 19 (1/2)
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 a.s.sumption 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 quant.i.ty 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.
uBER DIE URSACHE DER VON SIMONSEN BEOBACHTETEN UNVOLLSTaNDIGKEIT DER VERGaHRUNG DER AUS HOLZ BEREITETEN ZUCKERFLuSSIGKEITEN.
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 const.i.tuents in their anhydride form ('pentosanes'). They yield readily to acid hydrolysis, and certainly const.i.tute 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 const.i.tuents 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 a.n.a.lyses 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 a.s.sumption 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