Kinetic and Mechanistic Study of Oxidation of L-Alanine by Acidic Solution of Chloramine-T in Presence of Chloro-Complex of Ir ( III ) as Homogeneous Catalyst

Abstract: The kinetics and mechanism of homogeneously Ir(III) chloride catalyzed oxidation of Lalanine by chloramine-T [CAT] in perchloric acidic medium in the temperature range 30 to 45 0 C have been studied. The reaction is carried out in the presence of mercuric acetate as a scavenger for chloride ion. The experimental results show first order kinetics with respect to the oxidant [CAT] and catalyst [Ir(III)] while positive effect with respect to substrate, i.e., L-alanine was observed. The reaction shows negligible effect of [Hg(OAc)2], [H + ] and ionic strength of the medium. Chloride ion positively influenced the rate of reaction. The reaction between chloramine-T and L-alanine in acid medium shows 1:1 stoichiometry. To calculate activation parameters, the reactions have been studied at four different temperatures between 30 to 45oC. A mechanism involving the complex formation between catalyst, substrate and oxidant has been proposed. Acetaldehyde has been identified chromatographically and spectroscopically as the final product of oxidation of L-alanine. Based on the kinetic data, reaction stoichiometry and product analysis, a reaction mechanism has been proposed and rate law has been derived.