ANODICALLY GENERATED MANGANESE(III) ACETATE FOR THE OXIDATION OF ALPHA-AMINO-ACIDS IN AQUEOUS ACETIC-ACID - A KINETIC-STUDY

Manganese(III) acetate was prepared by the oxidation of manganese(II) acetate in aqueous acetic acid by electrolytic method. The anodically generated Mn(III) species was characterised by spectroscopic and redox potential studies. Conditions for the study of kinetics of Oxidation of alpha-amino acids by Mn(III) in aqueous acetic acid was investigate d. Plots of log[Mn(III)] versus time for the first order process, or M n(III) versus time for zero order process were nonlinear. The rate con stants computed from [Mn(III)](1/2) versus time plots were independent of [Mn(III)](0) indicating that the reaction goes through competitive zero and first order path-ways in [Mn(III)](0). The kinetic order in [amino acid], [H+] and [Mn(II)] were found out. Effect of added anions like CH3COO-, F-, Cl- and ClO4- were investigated. Evidence for the t ransient existence of the free radical reaction intermediate is given. Dependence of reaction rate on temperature is explained and activatio n parameters computed from Arrhenius and Eyring plots. A mechanism con sistent with the observed results is proposed and discussed.