Zirconia-supported sodium decatungstate (Na4W10O32/ZrO2):: An efficient, green and recyclable photocatalyst for selective oxidation of activated alcohols to carbonyl compounds with O2

Zirconia-supported sodium decatungstate, Na4W10O32/ZrO2, was prepared by incorporating Na4W10O32 cluster into zirconia matrix via a sol-gel technique and used as a green and recyclable heterogeneous photocatalyst for oxidation of a variety of benzylic alcohols with O-2 in CH3CN which resulted in the corresponding aldehydes and ketones selectively in moderate to excellent yields. High inter- and intra-molecular chemoselectivities were observed when benzylic OH groups were oxidized in the presence of aliphatic OH groups. Non-benzylic alcohols were less reactive under the conditions established here. The photocatalyst has been reused several times, without observable loss of activity and selectivity. Heterogeneous photocatalyst is more active than the unsupported Na4W10O32. (c) 2007 Elsevier B.V. All rights reserved.