Kinetics and mechanism of (salen)MnIII-catalysed oxidation of organic sulfides with sodium hypochlorite

The oxidation of organic sulfides with several substituted oxo(salen)manganese(V) complexes was investigated in 90% acetonitrile–10% water and the reaction is second-order overall, first-order each in sulfide and complex. Electron-releasing substituents in sulfides and electron-withdrawing substituents in oxo(salen)manganese(V) complexes accelerate the rate of oxidation. The second-order rate constants for the oxidation of p-substituted phenyl methyl sulfides follow a linear Hammett relationship with ρ = −1.85. However, correlation between log k2 and 2σ is excellent with ρ = 0.48 for the oxidation of thioanisole by substituted oxomanganese(V) complexes. The rate of oxidation of alkyl phenyl sulfides and dialkyl sulfides with oxo complexes was also examined and the reactions show a moderate steric effect. Substituent, acid and solvent effect studies reveal the operation of an SN2 mechanism. Copyright © 2003 John Wiley & Sons, Ltd.