Oxidation of organic sulfides by a vanadium(5+) oxo–monoperoxo–picolinate complex: Kinetics and mechanism

Abstract

The kinetics of oxidation of p-X-benzyl phenyl- and p-Y-phenyl benzyl sulfides by V(V) oxo–monoperoxo complex [PicVO(O 2)] (Pic = picolinic acid anion) in acetonitrile at 20 °C is reported. The oxidation reaction leads to the formation of the corresponding sulfoxides and to oxygen produced from the oxidant decomposition started by the substrate. The change of the obtained sulfoxide-emitted oxygen ratio in p-Y-phenyl benzyl sulfides seems to be due to the substituent type used in the substrate, whereas when the substituent is isolated from the reaction centre, as in p-X-benzyl phenyl sulfides, the sulfoxide and oxygen emitted are not influenced by the substituent. Moreover the products obtained from the oxidation of some p-X-toluenthiols (the corresponding aldehydes) suggest the hypothesis of a possible pathway for the oxygen transfer step for these reactions. The process seems to require coordination of the organic sulfide to the metal, followed by oxidation within the coordination sphere.