Synthesis of coumarins via Pechmann condensation using inorganic ion exchangers as solid acid catalysts

Abstract

This study involves synthesis and characterization of amorphous and crystalline M(IV) phosphates and tungstates, which are inorganic ion exchangers of the class of tetravalent metal acid (tma) salts. Presence of protons contained in structural hydroxyl groups indicates good potential for application in solid acid catalysis. Catalytic activity of materials has been explored by studying Pechmann condensation as a model reaction, wherein phenols (resorcinol, pyrogallol and phloroglucinol) have been treated with methyl acetoacetate to give coumarins, under solvent free conditions. Catalytic activity has been compared and correlated with surface properties of materials.