Kinetic and mechanistic studies of oxidation of chloramphenicol by sodium metaperiodate using Rh(III)-chloride as homogeneous catalyst

Abstract

The kinetics of oxidation of an antibiotic drug, chloramphenical(CHP) by NaIO₄ in the presence of Rh(III) catalyst has been investigated in alkaline medium at 35⁰C. The reaction shows first order kinetics with respect to [IO₄^-] and [Rh(III)]. The fractional positive order kinetics in [OH^-] and [CHP] throughout their variations were observed. It was found that ionic strength and dielectric constant of the medium had no effects on the rate of reactions. There is no effect of [Cl^-] in presence of Rh(III) chloride. The values of rate constants observed at four different temperatures were utilized to calculate various activation parameters. The species [IO₄^-] and [RhCl₃(H₂O)₂OH]^- are assumed as the reactive species of NaIO₄ and Rh(III) respectively in alkaline medium. On the basis of kinetic results, spectroscopic information and activation parameters, a suitable mechanism and rate law for the oxidation of CHP has been proposed.