336 STERN : THE SO-CALLED (( HYDROCELLULOSE.” XXXVII. - The So- ca Ued “ Hychocellulose.” By ARTHUR LANDAUER STERN, D.Sc. IT is well known t h a t all kinds of cellulose, when exposed to the action of certain reagents, lose their tenacity and become friable. This fact has hitherto been explained as being the result of the hydration of the cellulose, leading to the formation of bydrocellulose. All the evidence concerning this change appears to be contained in the work of A. Girard (Compt. vend., 1875, 81, 1105-1108; 1879, 88, 1322-1324 ; and Ann. China. Phys., 1881, [ v], 24, 337-384), who prepared hydrocellulose by several different methods, and having determined its empirical composition found this to agree fairly well with the formula C,,H,,O,l. The results of certain experiments carried out by the author in the course of another investigation threw doubt on the accuracy of Girard’s observations, and consequently some of his experiments were repeated.Girard prepared hydrocellulose by treating cellulose with cold sulphuric acid (sp. gr. 1-45), by the action of cold moist hydrogen chloride on air-dried cellulose, and by heating cellulose with dilute acids. The attempts made to prepare hydrocellulose by the first two of these methods proved unsuccessful, but the action of boiling 5 per cent. sulphuric acid on flax or cotton cellulose soon destroyed the tenacity of the fibres and converted the substance into a friable mass. As the change of 2C,H,,O, into CJ322011 is accompanied by an increase in weight of 5.6 per cent., it should be possible to detect this by quantitative experiments, Girard, however, states that under the most favourabie conditions the weight of hydrocellulose obtained is less than the weight of the original cellulose, and he explains this discrepancy by assuming that d-glucose is simultaneously produced, but adduces no evidence in support of this assumption beyond the fact that, after the reaction, the acid solution reduces Fehling’s soln tion.Experiments made to determine the relation between the weight of the cellulose taken and ( A ) the weight of the hydrocellulose and ( B ) the weight and nature of the other products of the reaction, gave the following results. A . (1) Flax cellulose, boiled for 24 hours in 5 per cent. sulphuric acid, lost 2.1 per cent., and was reduced to a powder.(2) Cotton cellulose, boiled for 1 hour with 5 per cent. sulphuric acid, similarly lost 3-9 per cent.STERN : THE SO-CALLED (( HYDROCELLULOSE.” 337 (3) Cotton cellulose, immersed in sulphuric acid (sp. gr. 1.45) for 16 hours at 26’, lost 3.3 per cent. ; the fibres mere rendered brittle, but were not converted into a powder. The following experiments show that this loss in weight is not a peculiar concomitant of the conversion of cellulose into hydrocellulose, but also occurs when hydrocellulose itself is submitted to the further action of the acid. The flax cellulose, which had been converted into hydrocellulose in the manner indicated by boiling with 5 per cent. sul- phuric acid for 2$ hours, was again submitted to the same process, when a further loss of 1.9 per cent.was observed, and the treatment being again repeated on the hydrocellulose remaining, there was an additional loss of 2.0 per cent. B. About 380 grams of purified cotton cellulose, covered with 5 per cent. sulphuric acid, were digested at 100” for 4 hours; the soluble matter was then filtered off and the ‘( hydrocellulose ” produced thoroughly washed with water. The sulphuric acid was removed from the solution by neut’ralisation with baryta, the precipitated barium sulphate filtered off, and the filtrate evaporated to a syrup in vucuo. This residue was treated with methyl alcohol, in which the greater portion dissolved. The total soluble products of the hydrolysis weighed 6.4 grams, or 1.8 per cent. of the cellulose employed. The syrup, which mas uncrystallisable, had an optical activity of + 37’ and a cupric reducing power K = 90 (d-glucose having K = 100).A portion of the syrup, when treated with phenylhydrazine acetate in the usual way, yielded a golden-yellow osazone closely resembling glucosazone, which crystallised in needles and melted a t 208’. Another portion, to which a small quantity of yeast had been added, lost 60 per cent. of its optical activity in a few days; the optical activity of the matter fermented was [a],=4So, and its K=107. All these facts indicate that one of the soluble products of the hydrolysis is d-glucose ; the amount obtained is, however, insufficient to explain Girard’s theory that the deficiency in the yield of hydrocellulose which is always found may be explaiied by the conversion of this deficiency in to d-glucose.The production of d-glucose in the conversion of ordinary cellulose into hydrocellulose is not, however, a peculiar characteristic of this change, as it is also formed when hydrocellulose is further acted on by hot dilute sulphuric acid. The hydrocellulose obtained in the last transformation was treated for a further period of 4 hours with 5 per cent. sulphuric acid a t 100”. The soluble products of the transformation, when separated in the same way, amounted to 5.3 grams, or 10.5 per cent. of the weight of hydrocellulose taken. A methyl-alcoholic solution of the syrupy product deposited crystals which had the following properties : c = 7.51 7 ; D = 3.972 ; [ aID = 36.9’ ;338 STERN : THE SO-CALLED '' HYDROCELLULOSE." Carbon ......Hydiogen ... and,afterrecrystallisation,gavethe following data: c = 2.582; D = 3.916; A solution of the recrgstallised product, when fermented with a small quantity of yeast, lost 58 per cent. of its optical activity in a few days, and another portion yielded a yellow, crystalline osazone resembling glucosazone and melting at 208'. The hydrocellulose residue of this reaction, when again treated in the same way, yielded 4.0 grams of soluble products, the methyl-alcoholic solution of which deposited crystals having the following properties : c = 4.778 ; D = 3.926 ; [ 0.1~ = 47.3' ; I< = 97.5. A portion put t o ferment with yeast lost 61 per cent. of its optical activity in a few days, and another portion yielded a yellow, crystalline osazone melting at 2 1 0 O .The hydrocellulose residue now remaining was again treated as before and 2.5 grams of soluble products were obtained, the methyl- alcoholic syrup of which gave crystals having the following properties ; c = 4.195 ; D = 3*S93 ; [ u J D = 45.6' ; K = 97.8. A portion of this sub- stance, when fermented with yeast for 10 days, a longer time than the previous fermentations, lost 97.8 per cent. of its optical activity, and another portion gave a yellow, crystalline osazone melting at 204'. Analysis of Hydroce1lulose.-Girard's results, which vary between 41.8 and 42.1 per cent. of carbon and 6.3-6.7 per cent. of hydrogen, although not very satisfactory, yet agree moderately well with the empirical formula C12H22011, which requires 42.1 per cent.of carbon and 6 4 per cent. of hydrogen. The celluloses employed in the present experiments mere burnt before and after having been exposed t o the action of acids as described above and yielded the following results : 45-90 ; K = 95-z.* 2i 4 I U 0 z E: 44.28 6-28 t ~ ____ ____ 44-39 44-44 44'27 _ _ _ _ - ~ 6-28 6'26 6'24 6 '22 - * c=Concentration in grams per 100 C.C. DZDiviaor ; a factor obtained by dividing the specific gravity minus 1, by c and multiplying the result by 1000. K =Cupric reducing power compared with that of d-glucoae as 100.STERN : THE SO-CALLED <' HYDROCELLULOSE." 339 Those figures agree very closely with the formula C,H1,O,. It appeared at first difficult to understand how Girard came to obtain his analytical figures, but this investigator's account of his experiments will render this quite clear.He states that hydrocellulose is easily oxidised on exposure to warm a i r ; at 80°, it becomes coloured, and at 100' this change takes place very rapidly. In several of the author's experiments, i t was found that, after the action of the acid, the cellulose, when washed in the usual way, was blackened on drying at loo", but in every case in which this took place, sulphuric acid was detected in the filtrate obtained by extracting the blackened mass with hot water. On the other hand, all the preparations of which the analyses are given above were dried in a current of dry air a t 100' ; in no case was the slightest colour produced, and the preparations did not contain sulphuric acid.As Girard's preparations becdme coloured when exposed to a temperature of looo, it is evident that they must have contained free acid, and as, on account of this, he only dried them at 35-40", it is extremely probable that they also contained water, and hence the low numbers obtained for the carbon and the high values for the hydrogen are explained. One of the author's specimens prepared by the action of sulphuric acid (sp. gr. 1.45) at 25" gave only 44.05 as the percentage of carbon, b u t in washing this specimen free from acid, a little ammonia had been added to one of the wash waters, and although it was thought that the cellulose had been properly washed, yet when another portion of the specimen was extracted with hot water, sulphuric acid was found in the filtrate, showing that a small amount of sulphate had been con- tained in the specimen burnt, thus accounting for the low percentage of carbon.It is evident from a consideration of these results that when cellu- lose is exposed to the action of hot dilute acids there is no formation of hydrocellulose ; the cellulose is partly hydrolysed with the produc- tion of soluble products, one of which is in all probability d-glucose. The cellulose residue, after exposure to the action of hot dilute acid for some hours, does not differ in elementary composition from the original cellulofie, but has been converted into a fine powder. A micro- scopic examination of the disintegrated cellulose at different stages of the reaction, shows that the disintegration is due to the fact that cer- tain portions of the fibre are more easily attacked than others, and when these portions of the fibres are converted into soluble products the whole fibre falls to pieces. Although this change is most marked i n the first stage of the reaction, yet each successive digestion results in the production of a finer product, until that obtained in the above- described experiments, after treatment for 16 hours, was so fine as to be most difficult to filter. The slowness of the action and the consequent long period of time340 CHATTAWAY : INTRAMOLECULAR REARRANGEMENT IN during which it was necessary to allow the hydrolysis to proceed in order to obtain a sufficient amount of soluble products, rendered it impossible to decide whether d-glucose was the only product of the hydrolysis or whether, as seems probable from Fenton's experiments, there are other soluble products (Trans., 1 98, 73, 554 ; 1899, 75, 423; 1901, 79, 361 and 807; and €'roc., 1901, 17, 166). Lsevulose, for example, would be destroyed in the foregoing experiments, owing to the protracted action of the hot acids.