Abstract

KINETIC AND THERMODYNAMIC STUDY FOR THE OXIDATION OF LEUCINE BY PERCHLORIC ACID SOLUTION OF CHLORAMINE-T IN PRESENCE OF Ir (III) IN ITS NANO CONCENTRATION RANGE AS HOMOGENEOUS CATALYST

Abhishek Verma, Jyoti Pandey, Reena Patel, Sheila Srivastava,*

ABSTRACT

The kinetics and mechanism of homogeneously Ir(III) chloride catalyzed oxidation of leucine by chloramine-T [CAT] in perchloric acidic medium in the temperature range 30 to 450C have been investigated. 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., leucine 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 leucine 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. Isopentaldehyde has been identified chromatographically and spectroscopically as the final product of oxidation of leucine. Based on the kinetic data, reaction stoichiometry and product analysis, a suitable reaction mechanism has been proposed and rate law has been derived.

Keywords: Kinetics, mechanism, Ir(III) catalysis, leucine, chloramine-T.