Nano composite mixed-addenda vanadium substituted polyoxometalate-TiO2 as a green, reusable and efficient catalyst for rapid and efficient synthesis of symmetric disulfides under ultrasound irradiation

Mixed-addenda vanadium substituted polyoxometalate supported on anatase TiO2 crushed nano leaf was synthesized by an unusual reaction with titanium tetraisopropoxide at 100 ºC via sol– gel method under oil-bath condition. The materials characterized by XRD, TEM, IR and UV– vis techniques. In the present work, efficient oxidative of thiols with polyoxometalate- TiO2/hydrogen peroxide system using ultrasound irradiation is reported. The Keggin type polyoxometalate-TiO2/H2O2, sandwich type POM-TiO2 and Wells Dowson type POM- TiO2/H2O2 systems showed completely different reactivity ordering for the same oxidation of thiols. Ultrasonic irradiation increased the catalytic activity of the catalyst, reduced the reaction times and increased the products yields.