Solvent effects on the kinetics of oxidation of methionine by nicotinium dichromate

Department of Chemistry, Gandhigram Rural Institute (Deemed University), Gandhigram-624 302, Tamilnadu, India E-mail : drkpelango@rediffmail.com Manuscript received 19 May 2005, revised 21 November 2005, accepted 1 June 2006 The oxidation of methionine by nicotinium dichromate (NDC) has been studied, in the presence of p-toluene sulphonic acid,in water-DMSO and water-acetic acid mixtures of varying mole fractions.The reaction is first order each with respect to NDC and acid. The reaction rates have been determined at different temperatures and the activation parameters have been computed.The rate of decomposition of the complex increases with increase in mole fraction of acetic acid in the mixture while in water-DMSO mixtures the rate decreases with increasing mole fraction of the organic co-solvent. A possible mechanism for the reaction is postulated