Researches on Cellulose Part 11

The latter very simply represents the formation of omega-brommethylfurfural from laevulose,[7]

------O----- H H OHC-----C---C---C--C-----CH_{2}OH H_{2} OH OH OH H

giving

H H HCC:CC:CCH_{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 Const.i.tution 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 a.n.a.lytical 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 const.i.tuents are easily isolated, and as they const.i.tute 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.

~Resume 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 a.n.a.lysis 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 pota.s.sium 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 a.s.sumed 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 ill.u.s.trated 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) _Const.i.tution of cellulose and oxycellulose._--The results of these investigations are generalised as regards cellulose (C_6) by the const.i.tutional 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.

QUANt.i.tATIVE SEPARATION OF CELLULOSE-LIKE CARBOHYDRATES IN VEGETABLE SUBSTANCES.

WILHELM HOFFMEISTER (Landw. Versuchs-Stat., 1897, 48, 401-411).

To separate the hemicelluloses, celluloses, and the const.i.tuents 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 vitae) 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.