Kinetic and thermodynamic study of Os(VIII) catalysed oxidation of glycine by ferrate(VI) in alkaline medium

Sheila Srivastava and Dharmraj Prajapati

Abstract

Kinetic and thermodynamic investigation on Os(VIII) catalysed oxidation of glycine by ferrate(VI) has been done in basic medium and in the temperature range 30– 450C. Rate of oxidation increases with increase in [FeO4] 2- and [Os(VI)]
and shows first order dependence. Rate of oxidation also increases with the increase in [S] but order is fractional. The rate decreases with an increase in pH. Rate of reaction is independent of [KCl], [KNO3] and change in ionic strength. The
values of rate constant observed at four different temperatures were used to calculate the activation parameters. The energy of activation (∆E*) of the reaction at pH 11 and temperature 350C was found to be 49.56 kJmol-1. [OsO4(H2O)2] and
[FeO4 2−] are proposed to be the reactive species of Os(VIII) and Fe(VI) respectively in the present investigation. Formaldehyde is found to be main product of the reaction along with carbon dioxide and ammonia as by products. On the basis of experimental findings, a suitable mechanism consistent with the observed kinetics is proposed and a rate law has been derived on the basis of obtained data.