An ammonium molybdate deposited amorphous silica coated iron oxide magnetic core–shell nanocomposite for the efficient synthesis of 2-benzimidazoles using hydrogen peroxide

Abstract

An ammonium molybdate deposited amorphous silica coated iron oxide (Fe₃O₄@SiO₂) magnetic core–shell nanocomposite was prepared and tested in the application to the synthesis of 2-benzimidazoles from aromatic aldehydes and o-phenylenediamines using hydrogen peroxide as an oxidant at room temperature. It was found that the yields were fundamentally influenced by the nature and position of the substituents on the phenyl ring. Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) confirmed that the active ammonium molybdate species are highly dispersed on the surface of the Fe₃O₄@SiO₂ magnetic core–shell nanocomposite, accounting for its good activity. A method was eventually developed for the synthesis of 2-benzimidazoles highlighting the good activity and easily recyclable nature of this magnetic catalyst.