Design, preparation and characterization of urea-functionalized Fe3O4/SiO2 magnetic nanocatalyst and application for the one-pot multicomponent synthesis of substituted imidazole derivatives

•A new urea-functionalized silica-based magnetite hybrid core-shell structure was prepared.•It showed excellent catalytic activity for the synthesis of substituted imidazoles.•The heterogeneous nanocatalyst was simply separated from the reaction mixture.•The catalyst was recycled several times without significant loss in catalytic activity.

Novel urea-functionalized silica-based magnetite hybrid core-shell nanoparticles were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analyses. It was used as a highly efficient and recoverable heterogeneous nanocatalyst for the one-pot three-component condensation reaction between benzil or benzoin with various substituted aldehydes and ammonium acetate to afford the corresponding imidazoles under mild reaction conditions in high-to-quantitative yields. The catalyst was recycled at least five times without significant decrease in the catalytic activity.

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