Studies On The Selective Oxidation Of Alkenyl Aromatics With Hydrogen Peroxide As Oxidant In The Presence Of Transition Metal Oxides

The selective oxidation of alkenyl aromatics is significant in organic chemistry,which can be widely used in food and pharmaceuticals.Zn₂V₂O₇ was prepared using ammonium metavanadate and zinc acetate as precursors.The catalytic activity of prepared sample was tested in the oxidation of styrene using hydrogen peroxide as oxidant.The reaction was carried out in acetonitrile under 60^oC,after stirring for 6 h,the conversion of styrene and the productivity of benzaldehyde were 88%and 81%,respectively.Other aromatic hydrocarbon could also be selectively transformed to corresponding aldehydes with the current catalytic system.An electron-donating group at the aromatic ring facilitated the formation of the corresponding aldehydes.The mechanism of the present oxidation reaction was discussed in this work.V₂O₅/g-C₃N₄ composites were successfully synthesized through a method of wet impregnation and calcination.The prepared samples were characterized by XRD,FT-IR,TG,XPS,BET,TEM,SEM,PL and UV-vis DRS.The loading of V₂O₅ could change the properties of g-C₃N₄ towards visible light and improve the charge separation efficiency of photoinduced charge carriers.V₂O₅/g-C₃N₄ composites with different loading of V₂O₅ exhibited different performance and a 3 wt%loaded composite was tested to be the optimal catalyst.Under optimal conditions,the conversion of styrene can reach 99%and the productivity of benzaldehyde was 87%.A plausible mechanism was proposed for this oxidation reaction with hydrogen peroxide as oxidant.Other styrene substrates were also selectively transformed to desired products with high yields（up to 92%）,using the developed catalytic system.