Abstract

CATALYSED OXIDATION OF ALLOPURINOL BY DIPERIODATOCUPRATE (III) PERIODATE COMPLEX IN AQUEOUS ALKALINE MEDIUM: A KINETIC APPROACH

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

Abstract

The kinetics of oxidation of the Allopurinol (ALP) bydiperiodatocuprate(III) (DPC) was carried in presence ofOsmium(VIII) catalyst in alkaline medium at constant ionic strength of0.01 mol dm-3 spectrophotometrically. The involvement of freeradicals was observed in the reactions. The stoichiometry is,[ALP]:[DPC] = 1:1. The reaction was first order in [DPC] and haspositive fractional order in [OH-] and negative fractional order in thecatalyzed cases. The order in [Osmium (VIII)] was unity. Amechanism involving the formation of a complex between ALP andOsmium (VIII) in case of catalysed reaction was proposed. Thereaction constants involved in the different steps of the mechanisms were calculated forreactions. The catalytic constant (Kc) was also calculated for catalysed reaction at differenttemperatures. The activation parameters with respect to slow step of the mechanisms werecomputed and discussed. The thermodynamic quantities were also determined for catalyzedreactions.

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