Catalytic properties of alkali metal-modified oxide supports for the Knoevenagel condensation: Kinetic aspects

The characterization of the alkali-modi fled metal oxides surface basicity by condensation of benzaldehyde with some methylenic compounds (ethyl cyanoacetate, ethyl acetoacetate and diethyl malonate) as test reaction were Studied with a series of lithium, sodium, potassium, rubidium and cesium impregnated simple oxide matrices (SiO2, Al2O3, Nb2O5 center dot nH(2)O and Nb2O5). The condensation of benzaldehyde and other substituted benzaldehydes with ethyl acetoacetate using these catalysts and in absence of any solvent, is also proposed as a green method in the preparation of pharmaceuticals in the line of calcium channel blockers and anti hypertensives. The role of the support nature in the Knoevenagel condensation activity is considered. (C) 2008 Elsevier B.V. All rights reserved.