Oxidation of Organic Sulfides by Quinolinium Chlorochromate: A Kinetic and Mechanistic Approach

Abstract

The oxidation of organic sulfides by quinolinium chlorochromate (QCC) resulted the formation of the corresponding organic sulfoxides. These reactions are first order ones with respect to QCC. A Michaelis-Menten type kinetics was observed with respect to the reactants. The reaction is catalyzed by p-toluene sulfonic acid (TsOH). The oxidation was studied in nineteen different organic solvents. An analysis of the solvent effect on Swain's equation showed that the both cation-and anion-solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of thirty-four sulfides were done in terms of various single and multiparametric equations. In the reactions of aryl methyl sulfides, the best correlation could be obtained with Charton's LDR and LDRS equations. The oxidation reactions of alkyl phenyl sulfides exhibited an excellent correlation in terms of Pavelich-Taft equation. The negative values of polar reaction constants indicate an electron-deficient sulfur center in the rate-determining step. The proposed reaction mechanism involves the formation of a sulphenium cation intermediate in a slow step * Corresponding AuthorsPhone: +91 94144-10900 E-Mail: drpkvs27@yahoo.com [a]