A Brønsted acidic ionic liquid anchored to magnetite nanoparticles as a novel recoverable heterogeneous catalyst for the Biginelli reaction

Abstract

In this study, simple and effective methods were used for the preparation of an ionic liquid that immobilized magnetite nanoparticles. Fe3O4nanoparticles were preparedviaa chemical co-precipitation method. Then, a SiO2shell was coated on the magnetic coreviathe Stober method. Finally, CPTES (chloropropyltriethoxysilane) and morpholine were coated on the SiO2shell. Morpholine sulfate, an acidic ionic liquid, was successfully bound to magnetite nanoparticles (Mag@Morph-AIL) and this was used as an efficient catalyst for the preparation of 3,4-dihydropyrimidinones. Compared to previous works, the easy separation of the nanocatalyst using an external magnet and the recyclability, non-toxicity, versatility, and high stability of the catalyst, combined with low reaction times and excellent yields, make the present protocol very useful for the synthesis of the title products. The synthesized products and catalyst were confirmedvia1H-NMR,13C-NMR, FT-IR, scanning electron microscope, X-ray diffraction, and elemental analysis.