Part 14 (1/2)

UEBER DIE KOHLENHYDRATE D. HEFE.

E. SALKOWSKI (Berl. Ber., 27, 3325).

~ON THE CARBOHYDRATES OF YEAST.~

The author has isolated the more resistant const.i.tuents of the cell-membrane by boiling with dilute alkalis, and exhaustively purifying with alcohol and ether.

The residue was only a small percentage (3-4 p.ct) of the original, and retained only 0.45 p.ct. N.

It was heated in a digester with water at 2-3 atm. steam-pressure, and thus resolved into approximately equal portions of soluble cellulose (a) and insoluble (b). The latter, giving no colour-reaction with iodine, is termed achroocellulose; the former reacts, and is therefore termed erythrocellulose. The former is easily separated from its opalescent solution. It has the empirical composition of cellulose. In the soluble form it resembles glycogen. The achroocellulose is isolated in the form of h.o.r.n.y or agglomerated ma.s.ses. It appears to be resolved by ultimate hydrolysis into dextrose and mannose.

SECTION V. FURFUROIDS, i.e. PENTOSANES AND FURFURAL-YIELDING CONSt.i.tUENTS GENERALLY

(1) ~Reactions of the Carbohydrates with Hydrogen Peroxide.~

C. F. CROSS, E. J. BEVAN, and CLAUD SMITH (J. Chem. Soc., 1898, 463).

(2) ~Action of Hydrogen Peroxide on Carbohydrates in the Presence of Ferrous Salts.~

R. S. MORRELL and J. M. CROFTS (J. Chem. Soc., 1899, 786).

(3) ~Oxidation of Furfuraldehyde by Hydrogen Peroxide.~

C. F. CROSS, E. J. BEVAN, and T. HEIBERG (J. Ch. Soc., 1899, 747).

(4) EINWIRKUNG VON Wa.s.sERSTOFFHYPEROXID AUF UNGESaTTIGTE KOHLENWa.s.sERSTOFFE.

C. F. CROSS, E. J. BEVAN, and T. HEIBERG (Berl. Ber., 1900, 2015).

~ACTION OF HYDROGEN PEROXIDE ON UNSATURATED HYDROCARBONS.~

The above series of researches grew out of the observations incidental to the use of the peroxide on an oxidising agent in investigating the hydrolysed furfuroids (102). Certain remarkable observations had previously been made by H. J. H. Fenton (Ch. Soc. J., 1894, 899; 1895, 774; 1896, 546) on the oxidation of tartaric acid by the peroxide, acting in presence of ferrous salts, the --CHOH--CHOH-- residue losing H_{2} with production of the unsaturated group, --OH.C=C.OH--. These investigations have subsequently been considerably developed and generalised by Fenton, but as the results have no immediate bearing on our main subject we must refer readers to the J. Chem. Soc., 1896-1900.

From the mode of action diagnosed by Fenton it was to be expected that the CHOH groups of the carbohydrates would be oxidised to CO groups, and it has been established by the above investigations (1) and (2) that the particular group to be so affected in the hexoses is that contiguous to the typical

--CO

group. There results, therefore, a dicarbonyl derivative ('osone'), which reacts directly with 2 mol. phenyl hydrazine in the cold to form an osazone. This was directly established for glucose, laevulose, galactose, and arabinose (2). While this is the main result, the general study of the product shows that the oxidation is not simple nor in direct quant.i.tative relations.h.i.+p to the H_{2}O_{2} employed. The molecular proportion of the aldoses affected appears to be in considerable excess, and the reaction is probably complicated by interior rearrangement.

In the main, the original aldehydic group resists the oxidation. But a certain proportion of acid products are formed, probably tartronic acid.

On distillation with condensing acids a large proportion of volatile mon.o.basic acids (chiefly formic) are obtained. The proportion of furfural obtained amounts to 3-4 per cent. of the weight of the original carbohydrate.