Kinetic and mechanistic investigation on oxidation of L-alanine and L-leucine byChloramine-T (CAT) using chloro-complex of Ir(III) in its nano-concentration range as homogeneous catalyst: A comparative study

Abstract

The kinetics and mechanism of homogeneously Ir(III) chloride catalysed oxidation of L-alanine (ala) and L-leucine (leu) by chloramine-T [CAT] have been investigated in a perchloric acidic medium in the presence of mercuric acetate as a scavenger in the temperature range 30ºC–45ºC. The reactions follow identical kinetics. The experimental results show the first order kinetics with respect to the oxidant [CAT] and catalyst [Ir(III)] while positive effect with respect to both of the amino acids were observed. It is found that that [Hg(OAc)2], [H+] and ionic strength(µ) of the medium have insignificant effect on the rate. Chloride ion is found to positively influence the rate of reaction. The reaction between chloramine-T and substrate (ala and leu) in acid medium shows 1:1 stoichiometry. The reactions have been studied at four different temperatures between 30 to 45 ºC and the activation parameters have been calculated. We have proposed a mechanism involving the complex formation between catalyst, substrate and oxidant. Acetaldehyde and isopentaldehyde have been identified chromatographically and spectroscopically as the final product of oxidation of ala and leu, respectively. Based on the kinetic data, reaction stoichiometry and product analysis, a suitable reaction mechanism has been proposed and the rate law has been derived. .