12-Tungstophosphoric acid supported on nano silica from rice husk ash as an efficient catalyst for direct benzylation of 1,3-dicarbonyl compounds in solvent-free condition

Nano silica has been prepared from rice husk, which is an agricultural waste, with high surface area and in amorphous form. 12-Tungstophosphoric acid, H3PW12O40 (PW) has been supported on this silica to produce nano silica supported PW (NPW/SiO2) as a nano catalyst. Characterization of this catalyst has been investigated by TEM, FTIR, and ICP, also, acidic properties have been studied by potentiometric titration method. 40% NPW/SiO2 has been used as a high effective catalyst for benzylation of 1,3-dicarbonyl compounds with benzylic alcohols. The present methodology offers a clean, practical, simple, mild, environmentally friendly, green and time-saving method under solvent free condition. Also, the catalyst is a good candidate for large-scale in direct benzylation of 1,3-dicarbonyl compounds. (C) 2011 Elsevier B.V. All rights reserved.