Oxidation studies with peroxomonophosphoric acid. II. A kinetic and mechanistic study of dimethyl sulfoxide oxidation in acid and alkaline media

The kinetics of dimethyl sulfoxide (DMSO) oxidation by peroxomonophosphoric acid (PMPA) in aqueous medium at 308 K and I = 0.4 mol/dm 3 follow the rate expressionsIn the pH range from 0 to 2, where k 1 and k 2 are 5.092 × 10 −1 dm 3 /mol sec and ≃ 0, respectively;in the pH range from 4 to 7, where k 2 = 8.127 × 10 −3 and k 3 = 2.90 × 10 −3 dm 3 /mol sec; andin the pH range from 10 to 13.6, where k 4 ≃ 0, and k 5 = 3.08 × 10 −2 dm 3 /mol sec. The reaction is interpreted in terms of mechanisms involving an electrophilic and a nucleophilic attack of the peroxomonophosphoric acid species, respectively, in acid and alkaline regions, on the sulfur atom of the sulfoxide molecule giving rise to S   N   2‐type transition states followed by oxygen‐oxygen bond fission to form the products.