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

The characterization of the alkali-modified 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·nH2O 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 antihypertensives. The role of the support nature in the Knoevenagel condensation activity is considered.