Detailed kinetic investigations of the oxidation of methyl phenyl sulphoxide and diphenyl sulphoxide by peroxomonosulphate in aqueous acetic acid medium reveal that the reactions are first-order, both in the sulphoxide and in the oxidant. Studies with substituted phenyl methyl sulphoxides and 4,4′-disubstituted diphenyl sulphoxides show that electron-releasing groups accelerate the rate of oxidation and electron-withdrawing groups retard it. A fair correlation between log k2 and Hammett substituent constants has been observed in the two series. The mechanism proposed involves the rate-determining nucleophilic attack of the sulphoxide sulphur at the outer terminal peroxo oxygen atom of HSO5−.
Volume 132, 2020
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