Kinetics and mechanism of oxidation of sugars by chromium (vi) in perchloric acid medium

Abstract

Kinetic data for the oxidation of D-glucose, fructose, maltose and sucrose by chromium (VI) in perchloric acid medium are reported The results of the reactions studied spectrophotometrically over a wide range of experimental conditions show that the rate· of the reaction is enhanced by increase in pH, ionic strength and concentrations of the sugars. The reactions are first-order with respect to both the sugars and Cr(VI) white the order with respect to [H] is complex. The order of reactivities of the sugars is fructose > maltose> glucose> sucrose. Formation of free radical intermediate complex was demonstrated and the kinetic results indicate the formation of a 1:1 intermediate complex between Cr(VI) and the sugars. The activation parameters have been evaluated and lend further support to the proposed mechanism.