Oxidation of Some Monosaccharides by Hexavalent Manganese in Aqueous Alkaline Medium: A Kinetic and Mechanistic Study

Article abstract of DOI:10.1002/kin.550270605

The kinetics of oxidation of some monosaccharides viz., D-ribose, D-xylose, and D-arabinose, D-glucose, D-fructose, D-galactose, 2-deoxyglucose, and α-methyl glucopyranoside by MnO4^2- in aqueous alkaline medium have been studied.The rate of oxidation has been found to be first-order both with respect to and .The rate is independent of under experimental conditions of > 0.5 M where the oxidant is stable.The effect of ionic strength is negligible on the rate.A mechanism involving the formation of a 5-membered cyclic intermediate complex between MnO4^2- and 1,2-enediol form of the sugar is proposed.The intermediate complex decomposes to give products in the subsequent slow step.The involvement of 1,2-enediol form receives support from the reaction of α-methyl glucopyranoside, which exists in ring structure in alkaline solution reacting much slower than glucose with MnO4^2- under similar conditions.Second-order rate constant k'' and activation parameters have been evaluated.The series of reactions exhibits a clear demonstration of applicability of isokinetic phenomenon where Arrhenius plots for all the reactions are found to intersect at a common point (295 K).