Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.
Carbohydr Polym. 2013 Feb 15;92(2):2321-6. doi: 10.1016/j.carbpol.2012.11.062. Epub 2012 Dec 10.
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.
已通过分光光度法研究了在恒定离子强度为 4.0 mol dm(-3) 下，作为硫酸化碳水化合物的硫酸软骨素 4-硫酸盐多糖在重铬酸中的动力学。反应动力学表明重铬酸呈一级依赖关系，而硫酸软骨素 4-硫酸盐浓度呈分数一级动力学。[H(+)对反应速率的影响表明氧化过程是酸催化的。添加的 Mn(2+)离子表明形成了 Cr(IV)作为中间物种。揭示了形成 1:1 中间络合物的动力学证据。已评估了动力学参数，并讨论了与获得的动力学结果非常一致的暂定反应机制。
