Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions.

Refat Hassan, Samia Ibrahim, Abdel Rahman Dahy, Ishaq Zaafarany, Fahd Tirkistani, Hideo Takagi

Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt. rmhassan2002@yahoo.com

Carbohydrate polymers 2013 Feb 15

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The kinetics of chromic acid oxidation of chondroitin-4-sulfate polysaccharide as sulfated carbohydrates at a constant ionic strength of 4.0 mol dm(-3) has been investigated, spectrophotometrically. The reaction kinetics showed a first-order dependence in chromic acid and fractional-first-order kinetics with respect to the chondroitin-4-sulfate concentration. The influence of [H(+)] on the reaction rates showed that the oxidation process is acid-catalyzed. Added Mn(2+) ions indicated the formation of Cr(IV) as intermediate species. A kinetic evidence for formation of 1:1 intermediate complex was revealed. The kinetic parameters have been evaluated and a tentative reaction mechanism in good consistent with the kinetic results obtained is discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Citation

Refat Hassan, Samia Ibrahim, Abdel Rahman Dahy, Ishaq Zaafarany, Fahd Tirkistani, Hideo Takagi. Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions. Carbohydrate polymers. 2013 Feb 15;92(2):2321-6