Magnetic carbon nanotube as a highly stable and retrievable support for the heterogenization of sulfonic acid and its application in the synthesis of 2‐(1H‐tetrazole‐5‐yl) acrylonitrile derivatives

In the present study, a novel magnetic carbon nanotube functionalized by chlorosulfonicacid (Fe3O4‐CNT‐SO3H) with nanotube morphology decorated by the spherical nanoparticles was prepared, characterized and introduced as a retrievable magnetic heterogeneous nanocatalyst for green synthesis a variety of 2‐(1H‐tetrazole‐5‐yl) acrylonitrile via multicomponent domino Knoevenagel condensation/ 1,3‐dipolar cycloaddition reaction between aromatic aldehydes, malononitrile, and sodium azide under solvent free conditions. The catalyst was magnetically separated from the reaction system by an outer magnetic force and recycled up to five runs without a remarkable loss in its efficiency. The as‐preparedacidic magnetic nanocomposite was characterized by different techniques inclusive Fourier transform infrared, thermogravimetric analysis, energy dispersive X‐ray, field emission scanning electron microscopy, X‐ray diffraction, vibrating sample magnetometry, CHNS elemental analysis, and acid‐base titration. Easy workup, affordability, elimination of volatile and toxic solvents, and high yield of products are some merits of this protocol.