Catalytic oxidation of ethylbenzene to acetophenone over Keggin structure molybdovanadophosphoric heteropoly compounds

A series of Keggin type heteropoly compounds,(Cpyr)3+xPMo12-xVxO40(in that Cpyr=(C16H32C5H4N)+,x=0,1,2,3),are synthesized and characterized.With 50% of aqueous hydrogen peroxide as oxidant,ethylbenzene can be efficiently oxidized to acetophenone over the prepared phase-transfer catalysts.The effects of catalyst type,amount of catalyst and H2O2,solvent,and reaction conditions are investigated.Under the following optimal conditions as followed:25 mmol of ethylbenzene,0.2 mmol of catalyst and 0.1 mol of H2O2(in mass concentration of 50%),70℃ as reaction temperature,and 25 mL of acetic acid as the solvent,a conversion rate of 80.75% for ethylbenzene can be obtained within 8 hours with a selectivity of 81.46% for acetophenone.