Sol-Gel Silica-Supported 12-Tungstosilicic Acid (H4SiW12O40/SiO2) as a Heterogeneous Photocatalyst for Efficient and Selective Oxidation of Benzylic Alcohols with O2 under Photoirradiation

Saeid Farhadi,* Zaynab Babazadeh and Mansoureh Maleki

Department of Chemistry, University of Lorestan, Khoramabad, Iran E-mail:

Sol-gel silica-supported heteropolyoxotungstate (H4SiW12O40/SiO2), prepared by incorporating H4SiW12O40 cluster into a silica matrix via sol-gel technique, was used as an efficient heterogeneous photocatalyst for oxidation of alcohols by O2. Irradiation of a series of primary and secondary benzylic alcohols in acetonitrile solvent over H4SiW12O40/SiO2 under O2 atmosphere resulted in the corresponding aldehydes and ketones selectively and in high yield. Non-benzylic alcohols were less reactive under the conditions estabilished here. The photocatalyst  has been reused several times, without observable loss of activity and selectivity. Eventually, heterogeneous photocatalyst considerably is more active than the unsupported H4SiW12O40..

Keywords: Photooxidation, Benzylic alcohols, Heterogeneous, Polyoxometalates, Photocatalyst, Sol-gel silica-supported