Nanoporous Na+-montmorillonite perchloric acid as an efficient heterogeneous catalyst for synthesis of merocyanine dyes based on isoxazolone and barbituric acid

Abstract

Nanoporous Na+-montmorillonite perchloric acid (MPA) as a novel heterogeneous solid acid catalyst was easily prepared. The physico-chemical properties of the catalyst were analyzed by a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) and nitrogen adsorption-desorption measurements, pH analysis and Hammett acidity function. The prepared reagent showed excellent catalytic activity for the green one-pot, three component synthesis of 3-methyl-4-arylmethylene-isoxazol-5(4H)-one, pyrano [2,3-d] pyrimidinone and 5-arylidine barbituric acid derivatives in aqueous media. The remarkable features of the present protocol are availability and low cost of the starting materials, reusability of the catalyst, short reaction times and high yields of the products.