Synthesis of 4H-benzo[b]pyrans in the presence of sulfated MCM-41 nanoparticles as efficient and reusable solid acid catalyst

Abstract

A one-pot three-component reaction of various types of aldehydes, dimedone, and malononitrile was studied in the presence of sulfated MCM-41 (SO4 2−/MCM-41) nanoparticles for the synthesis of 4H-benzo[b]pyrans. MCM-41 was synthesized in nanosize by the sol–gel method and then SO4 2−/MCM-41 samples with different calcination temperatures were prepared and characterized by XRD, FT-IR, SEM, and BET techniques. The characterization results show the insertion of sulfate in the mesoporous structure of MCM-41 and the catalytic performance experiments show that SO4 2−/MCM-41 with a calcination temperature of 550 °C has the best catalytic activity. The reusability experiments show that the catalyst is reusable with moderate decrease in activity.