THE CONSTITUTION OF A SYNTHETIC XYLAN: I. GENERAL STRUCTURAL FEATURES

Abstract

The polysaccharide was obtained by polymerization of D-xylose at 140 °C in the presence of phosphorous acid. Complete hydrolysis of the xylan followed by bromine oxidation showed that the synthetic polymer contained only xylose. Periodate oxidation resulted in formation of a considerable quantity of formaldehyde, the origin of which is not known. Periodate oxidation of borohydride-reduced xylan gave additional formaldehyde and, from this, the average D. P. of the polymer was estimated to be about 55. Complete hydrolysis of the polyalcohol gave ethylene glycol, glycerol, and xylose in a ratio of 2:9:1. Partial hydrolysis gave ethylene glycol, glycerol, and at least seven non-reducing components. Hydrolysis of the fully methylated xylan gave tri-, di-, mono-methyl xyloses and xylose in a 32:32:18:5 ratio, and a carbonyl band was evident in the infrared spectrum of the hydrolyzate. No such band was evident in the hydrolyzate of the unsubstituted xylan. The xylan is highly branched and contains some D-xylofuranose units.