Selective oxidation of alcohols to aldehydes using inorganic-organic hybrid catalyst based on zinc substituted polyoxometalate and ionic liquid

摘要

Various organic-inorganic hybrid compounds, [bmim]_x[PW_(11)MO_(39)]-3H_2O {(bmim: 1-n-butyl-3-methylimidazolium) and [M = V(IV), Cr(III), Mn(II), Fe(IIl), Co(II), Ni(II), Cu(II), Zn(Il)]}, were prepared and characterized by elemental analysis, UV-Vis, FT-1R, and TGA. The synthesized hybrid compounds were used as catalysts in oxidation of various alcohols with hydrogen peroxide in acetonitrile. The effect of the transition metal on the catalytic activity was in the order, Zn > Fe > Ni > Cr > Co > V > Mn > Cu. In this catalytic system, the effects of other parameters such as the type of solvent, amount of oxidant and catalyst, and the temperature were also investigated. [bmim]_5[PW_(11)ZnO_(39)] ? 3H_2O was reused several limes without loss of catalytic activity.