Oxidation reactions catalyzed by polyoxomolybdate salts

Ionic compounds containing the polyoxomolybdate anion [Mo₆O ₁₉]^2- and [(n-C₄H₉) ₄P]⁺ (tetra-butylphosphonium), [(n-C₄H ₉)₃P(n-C₁₄H₂₉)]⁺ (tributyl (tetradecyl)phosphonium), [Bmim]⁺ (1-butyl-3- methylimidazolium) and [Dbmim]⁺ (1,2-dimethyl-3-butylimidazolium) cations were prepared and characterized, including the determination of three of the solid state structures by singlecrystal X-ray diffraction. These compounds were applied as catalysts for the epoxidation of olefins with urea hydrogen peroxide (UHP) as oxidant in the ionic liquid [Bmim]PF₆. Additionally, the oxidation of sulfides to sulfoxides with hydrogen peroxide (H₂O₂) in several solvents was investigated. The polyoxomolybdate catalysts showed a good performance for epoxidation of olefins as well as for oxidation of sulfides. Furthermore, the catalysts can be recycled several times in oxidation reactions. We present this methodology for the oxidation reaction in a simple, economically, technically, and environmentally benign manner.