Kinetics and mechanism of oxidation of <img src='http://www.niscair.res.in/jinfo/smaller.gif' border=0>-glucose by chromium(VI) in perchloric acid

Abstract

The oxidation of <img src='http://www.niscair.res.in/jinfo/smaller.gif' border=0>-glucose with Cr(VI) in aqueous perchloric acid proceeds via formation of a 1:1 complex which is considered to be chromium (VI) bonded to anomeric-OH group. The complex is formed within the time of mixing and remains stable for ≥ 24h in the absence of perchloric acid. The reaction products are <img src='http://www.niscair.res.in/jinfo/smaller.gif' border=0>-1,4-glucolactone and Cr(III). Formation of CO₂ has not been observed during the course of reaction under the experimental kinetic conditions. The reaction rate increases with [HClO₄] and no acid-independent path has been observed. Manganese(II) inhibits the reaction rate and the order is found to be zero in [manganese(II)]. The kinetics of electron-transfer reactions to yield Cr(III) have been investigated spectrophotometrically and, on the basis of experimental data, mechanisms are presented and discussed .