Brønsted Acidic Dicationic Ionic Liquid Immobilized on Fe3O4@SiO2 Nanoparticles as an Efficient and Magnetically Separable Catalyst for the Synthesis of Bispyrazoles

In this research article, brønsted acidic dicationic ionic liquid immobilized on silica‐coated iron oxide support and its catalytic activity was investigated in the synthesis of bis‐pyrazol‐5‐ols under solvent‐free conditions. The prepared catalyst was characterized by different analytical tools such as XRD, FT‐IR, TGA, TEM, and SEM techniques. The catalyst can be recycled at least five times with the remaining of its catalytic activity. The easy recovery, reusability, and excellent activity of the catalyst as well as easy workup are other remarkable advantages of this method. Fe3O4@SiO2/brønsted acidic dicationic ionic liquid was prepared and applied as magnetically and efficient nanocatalyst in the synthesis of 4,4′‐(aryl methylene) bis (3‐methyl‐1H‐pyrazole‐5‐ol)s under solvent‐free condition. A variety of benzaldehyde was used to afford the corresponding bis pyrazoles, the catalyst could be easily separated by using external magnet from the reaction mixture and reused five times without significant loss of catalytic activity.