Synthesis a polymer-supported Fe3O4 nanoparticles and its application as a novel route for the synthesis of imidazole derivatives

Magnetic iron oxide nanoparticles (MNPs) have attracted much attention than other nanoparticles arising from their unique physicochemical properties, great potential biomedical applications, large surface area, and fast response under applied external magnetic field and low Curie temperature [1-3]. Also polymeric reagents compared to monomeric reagents and catalysts benefit from important advantages including: insolubility in the reaction mixture and thus their rapid and simple workup, efficient reducing of the leaching of chemicals into reaction, solvent or environment in work-up procedures, safe handling, reusability of the reagents and reduction of environmental pollution in the presence of them because of their easy isolation by simple filtration. So by combining the positive properties of magnetic nanoparticles and polymeric reagents, we have a class of polymeric reagents and catalyst which shown excellent magnetic properties [4-6]. In this work cross-linked poly (4-vinylpyridine) supported Fe3O4 nanoparticles abbreviated as [P4-VP]-Fe3O4NPs, was easily prepared as a new magnetic polymeric catalyst and efficiently used for the synthesis of imidazole. The Polymeric catalyst was characterized using various techniques including: field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FT-IR) techniques. According to the obtained results of these techniques a good dispersion of Fe3O4 nanoparticles on the polymer support and also excellent magnetic property of the catalyst were approved. A novel method for the synthesis of imidazole derivatives also has been developed by one-pot condensation reaction of benzil, ammonium acetate and aldehydes in the presence of [P4-VP]-Fe3O4 nanoparticles. The catalyst displayed good catalytic activity when applied in one-pot condensation reaction of benzil, ammonium acetate and aldehydes. Various imidazole derivatives are prepared in high to excellent yields (79-99%) with short reaction times and high purity. The imidazole products were characterized by FT-IR, 1H and 13C NMR spectroscopy and melting points. The physical properties were compared to the literature values of known compounds. The present method benefit from some advantages over conventional classical methods such as rapid and very simple work-up and also the catalyst is reusable many times without a significant loss in its activity.