Reaction between Carbohydrates and Sulfuric Acid. (2). Depolymerization and Sulfation of Chondroitin Sulfate by Sulfuric Acid

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When chondroitin sulfate was dissolved in concentrated sulfuric acid, sulfation and depolymerization took place simultaneously during dissolution, and subsequent depolymerization developed gradually with reaction time which had no effect on sulfation. The degree of depolymerization depended on reaction temperature which had a slight effect on sulfation. The degree of sulfation was decisively controlled by temperature at the time of ether addition to the reaction mixture for the separation of products. By controlling various reaction conditions, i.e., reaction time, reaction temperature, and temperature at the time of ether addition, sulfated chondroitin with various combinations of molecular weight and sulfur content was obtained. The distribution of molecular size in sulfated chondroitin was investigated by gelfiltration, which suggested a high polydispersity in molecular weight. Chemical analyses of sulfated chondroitin revealed that neither degradation of the uronic acid residue nor deacetylation of the N-acetylgalactosamine residue occurred. The data of periodate oxidation and infrared spectra suggested that the three substitutable hydroxyl groups present in the unit disaccharide of chondroitin sulfate were randomly sulfated.