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.