STUDIES OF URONIC-ACID MATERIALS .52. DEGRADATION OF ACIDIC POLYSACCHARIDES DURING STRUCTURAL-ANALYSIS INVOLVING PERMETHYLATION

The extent of the degradation of gum exudates from Acacia and Combretum spp. in different methylation procedures has been studied. Methylation of C. nigricans gum with the sodium hydride-iodomethane-dimethyl sulphoxide system caused losses of rhamnose and galacturonic acid that did not occur with two other systems. In a study of the extent of the degradation suffered by the gums from Acacia seyal and Combretum nigricans during methylation with the Haworth method, partially methylated products, isolated at intervals during the reaction, were analysed: C. nigricans gum suffered much more rapid and extensive degradation than A. seyal gum; this degradation must be taken into account in structural analyses of gums of the Combretum genus. © 1979.