The Insoluble Carbohydrates of Wheat (grain).
H. C. Sherman (J. Amer. Chem. Soc., 1897, 291).
(p. 171) This is a study of the constituents of the cell-walls of wheat grain. Bran was taken as the most convenient form of the raw material, being freed from starch by treatment with malt extract, and further treated (1) with cold dilute ammonia, (2) cold dilute soda lye (2 p.ct. NaOH), and (3) boiling 0.1 p.ct. NaOH. The product retained only 1.25 p.ct. proteids, and yielded 15.62 p.ct. furfural.
Acid Hydrolysis.—The product was boiled 30 mins. with dilute acid (1.25 p.ct. H2SO4), and the solution boiled until the Fehling test showed no further increase of monoses. At the limit the reducing power of the dissolved carbohydrates was 91.3 p.ct., that of dextrose. Converted into osazones the analysis showed them to be pure pentosazones. The hemicellulose of wheat is, therefore, according to the author, pure pentosane.
Residue.—This was a lignocellulose yielding 11.5 p.ct. furfural. It was subjected to a series of treatments with ferric ferricyanide, and the proportion of Prussian blue fixed was determined by increase of weight, viz. from 10 p.ct. to 47 p.ct. according to the conditions. The results confirmed those of Cross and Bevan first obtained with the typical lignocellulose (jute).
Chlorination.-The residue was boiled with dilute alkali, washed, and exposed to chlorine gas. The resulting lignone chloride was isolated by solution in alcohol, &c. It yielded 26.7 p.ct. Cl on analysis. In this and its properties it appeared to be identical with the product isolated by Cross and Bevan from jute, with the empirical formula C19H18Cl4O9.
Cellulose was isolated from the residue by three of the well-known methods, and the following comparative numbers are noteworthy:
| Method | F. Schulze Dil. HNO3 KClO3 | Lange Fusion KOH | Cross and Bevan Chlorine, &c. |
| Cellulose p.ct. obtained | 66.0 | 39.3-43.1 | 66.5 |
| Furfural p.ct. of cellulose | 7.0 | 3.96 | 5.62 |
| Residual nitrogen | 0.22 | 0.03 | 0.00 |
| Ferricyanide reaction, Prussian blue fixed | 6.04 | 0.89 | 0.92 |
The author remarks: 'It is evident no one feature can be urged as a criterion in judging between the methods, but all must be taken into consideration. Such a comparison shows the superiority of the chlorination method.'