PWA/montmorillonite K10 catalyst for synthesis of coumarins under solvent-free conditions

12-Tungstophosphoric acid supported on montmorillonite K10 (PWA/mont-K10) catalysed Pechmann condensation reaction was reported. The catalyst was characterized by XRD, FTIR, UV–Vis DRS, surface area and pore size analysis, TGA and acidity by DRIFTS using pyridine. The morphology of the catalyst was studied by SEM. The activity of mont-K10, mont-KSF, $$ {{{\text{SO}} ₄^{{ 2 {-}}} } \mathord{\left/ {\vphantom {{{\text{SO}} ₄^{{ 2 {-}}} } {{\text{ZrO}} ₂ }}} \right. \kern-\nulldelimiterspace} {{\text{ZrO}} ₂ }} $$ , 12-tungstophosphoric acid, and PWA/mont-K10 was investigated by condensation reaction of resorcinol with ethyl acetoacetate in the absence of solvent. Effect of molar ratio, amount of catalyst, reaction temperature and time on the yield of 7-hydroxy-4-methylcoumarin had been investigated on PWA/mont-K10. PWA/mont-K10 catalysed condensation of ethyl acetoacetate with phenol and a few substituted phenols had also been carried out to yield corresponding coumarins. The recycled catalyst showed reduced activity after single use. 15 wt% PWA on mont-K10 was found to be effective for synthesis of coumarin derivatives without employing any solvent.