Single step synthesis of coumarin derivatives over Al-MCM-41 and its supported catalysts under solvent-free condition

Al-MCM-41 (Mobil Composition Mater) (Si/Al = 25) molecular sieve was synthesized hydrothermally and 20 and 40 wt% phosphotungstic acid (PW) was supported on it. The materials were characterized using XRD, pyridine adsorbed FT-IR, 31P and 1H MAS NMR techniques. Catalytic performance of the materials was examined in the liquid phase condensation of resorcinol and ethyl acetoacetate. 7-Hydroxy-4-methylcoumarin was the only product observed in this reaction. The results revealed that 20 wt% PW/Al-MCM-41 is found to be more active than other catalysts. The reaction parameters were optimized to obtain high selectivity of the desired product at maximum resorcinol conversion. The reaction was also performed with substituted phenolic derivatives and ethyl acetoacetate in order to realize the substituent effect.

Graphical abstractPechmann reaction has been extensively used for the preparation of coumarin and its derivatives from simple starting materials. The present investigation describes an ecofriendly route for the Pechmann synthesis of coumarin derivatives over Al-MCM-41 and its supported catalysts under solvent-free condition. Figure optionsDownload full-size imageDownload as PowerPoint slide