Abstract

DETERMINATION OF THERMODYNAMIC PARAMETERS OF Ru(III) CATALYSED OXIDATION OF ALLOPURINOL BY Cu(III) PERIODATE COMPLEX IN ALKALINE MEDIUM: A KINETIC STUDY

Javed I. Moodi, Asma M. Tatagar and S. D. Lamani*

Abstract

The kinetics of oxidation of the Allopurinol (ALP) by diperiodatocuprate (III) (DPC) was carried in presence of Ruthenium (III) catalyst in alkaline medium at constant ionic strength of 0.01 mol dm-3 spectrophotometrically. The involvement of free radicals was observed in the reactions. The stoichiometry is, [ALP]:[DPC] = 1:2. The reaction was first order in [DPC] and has positive fractional order in [OH-] and negative fractional order in the catalyzed cases. The order in [Ruthenium (III)] was unity. A mechanism involving the formation of a complex between ALP and Ruthenium (III) in case of catalysed reaction was proposed. The reaction constants involved in the different steps of the mechanisms were calculated for reactions. The catalytic constant (Kc) was also calculated for catalysed reaction at different temperatures. The activation parameters with respect to slow step of the mechanisms were computed and discussed. The thermodynamic quantities were also determined for catalyzed reactions.

Keywords: Allopurinol; Diperiodatocuprate (III); Ru (III)catalysis; Oxidation; Kinetics.