Mechanism of oxidation of aryl methyl sulfoxides with sodium hypochlorite catalyzed by (salen)MnIII complexes

Abstract The oxidation of organic sulfoxides to sulfones with sodium hypochlorite catalyzed by (salen)Mn III complexes in 90% acetonitrile–10% water (v/v) follows an overall second-order kinetics, first-order each in the oxo complex and the substrate. The less nucleophilic sulfoxides are more sensitive to substituent effect ( ρ  = −2.57) compared to the corresponding sulfides ( ρ  = −1.85). A positive ρ -value ( ρ  = 0.50) is observed in the oxidation of phenyl methyl sulfoxide by substituted oxo(salen)manganese(V) complexes. Substituent, acid and solvent effect studies reveal the operation of a common S N 2 mechanism. Correlation analyses establish that there is an inverse relationship between reactivity and selectivity in both the sulfoxide and complex series. A valid reactivity–selectivity principle (RSP) is observed in this redox system.