Magnetite-Containing Sulfonated Polyacrylamide as a Nanocatalyst for the Preparation of Biscoumarins

Abstract

Magnetite-containing sulfonated polyacrylamide was easily prepared through polymerization of the corresponding monomers followed by the reaction with Fe₃O₄ nanoparticles. The characterization of the obtained catalyst was performed by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The acidic SO₃H moiety was found to be 1.1 mmol per gram of the obtained polymer. The catalytic activity of the polymer was examined for the synthesis of biscoumarin derivatives by two-component one-pot domino Knoevenagel-type condensation/Michael reaction between aldehydes and 4-hydroxycoumarin. Biscoumarins were obtained in high to excellent yields in short time. The work-up procedure of this reaction was very simple. The catalyst is stable (as a bench top catalyst) with easy-handling and it can be used again.