Kinetics and mechanism of the oxidation of DL-methionine by quinolinium bromochromate

Department of Chemistry, J. N. V. University, Jodhpur-342 005, Rajasthan, India E-mail : drpkvs27@yahoo.com R. D. National College, Bandra West, Mumbai University, Mumbai-400 050, India Manuscript received 26 June 2007, revised 3 January 2008, accepted /0 January 2008 The oxidation of methionine (Met) by quinolinium bromochromate (QBC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding sulphoxide. The reaction is of first order with respect to each QBC and Met. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form : kobs = a + b (H+]. The oxidation of methionine was studied in nineteen different organic solvents. The solvent effect was analyzed by Kamlet's and Swain's multiparametric equations. Solvent effect indicated the importance of the cation-solvating power of the solvent. A suitable mechanism has also been postulated