Synthesis of arylidene propanedioic acids by Knoevenagel condensation for use in ceramic sols

This paper is primarily concerned with the synthesis of arylidene propanedioic acids by Knoevenagel condensation. Generally organic bases pyridine and piperidine are used as catalyst in Knoevenagel condensation which are costly and health hazard. In this research work, Knoevenagel condensation of various aromatic aldehydes (benzaldehyde, salicylaldehyde and p-chlorobenzaldehyde) and active methylenes (malonic acid and ethyl acetoacetate) was carried out in the presence of amino acids (glycine, lysine, hippuric acid, methionine and leucine) as catalyst. Using salicylaldehyde gave coumarin-3-carboxylic acid, a solvent free synthesis. These products were isolated and purified and were characterized through melting points, TLC, IR, mass and ¹H NMR. These acids are synthesized for eventual development of organically modified ceramic nano powders.