Kinetics and mechanism of the oxidation of organic sulphides by <i>N</i>‐chloroacetamide

Abstract

Abstract The kinetics of the oxidation of a number of monosubstituted aryl methyl, alkyl phenyl, dialkyl and diphenyl sulphides by N ‐chloroacetamide (NCA) to yield the corresponding sulphoxides were studied. The reaction is first order with respect to the sulphide, NCA and hydrogen ions. There is no effect of added acetamide. Protonated NCA has been postulated as the reactive oxidizing species. The rates of oxidation of meta ‐ and para ‐substituted phenyl methyl sulphides were correlated with Taft's and Swain's dual substituent parameter equations. For the para ‐substituted compounds, the best correlation is obtained with σ I and σ ; the meta ‐substituted compounds correlate best with σ I and σ R ° values. The reaction constants are negative. The oxidation rates of the ortho ‐substituted sulphides yield an excellent correlation in a triparametric equation involving Taft's σ I and σ values and Charton's steric parameter, V . The oxidation of alkyl phenyl sulphides is susceptible to both polar and steric effects of the alkyl group. A mechanism involving the formation of a halogenosulphonium cation in the rate‐determining step is proposed.