Studies on the Hemicelluloses

Hemicellulose prepared from Elm wood, Ulmus Davidiana Planch. var. japonica NAKAI, yields the glycosides of 2, 3-dimethyl xylose and 2- or 3-monomethyl xylose in the approximate molecular ratio 8:1 upon methanolysis of the methyl ether derivative. Accordingly, it seems evident that, in the original hemicellulose, wherin eight molecules of xylose are associated with one residue of xylogluconic acids, the xylose residues consist of two types one combines with the adjacent residues C1 and C4 and the other has only one hydroxyl group situated in C2 or C3 and combines through the three positions of C1, C4 and C2 or C3 with other residues, and that the molecular ratio of the former to the latter is 8 to 1 approximately. It appears that only β-xylose residues are concernd in this hemicellulose, since the specific rotation of the hemicellulose (-96.0°) is analogous to that of β-mehyl xyloside (-67°) but very different from that of α-methyl xyloside(+153°).