Periodate oxidation analysis of carbohydrates: Part IX. Evaluation of the use of pyridine as reaction solvent for oxidation of water-insoluble carbohydrate materials

Oxidation of methyl glycopyranosides with periodic acid in pyridine was studied by analysis of the reaction products by the dithioacetal method. Both C₂—C₃ and C₃—C₄ bonds were cleaved yielding three types of dialdehydes;secondary attack of these dialdehydes by periodic acid did not occur. Oxidation in aqueous pyridine proceeded in normal Malapradian fashion, but more slowly than for oxidation in water. Molar proportions of aldehydes were theoretical, when methyl glycosides were oxidized with periodic acid in a 1:1 ($\text{v}\text{v}$) mixture of pyridine and water. The structures of carbohydrate moieties in a few saponins and glycolipids were confirmed by analysis of the oxidation products obtained under similar conditions.