Iron Nanoparticles in Green Solvents: A Sustainable Catalytic Route to Access Imidazole Derivatives

ABSTRACT

Imidazole scaffolds form a privileged group of heterocycles with a large presence in pharmaceuticals, agrochemicals, and functional materials due to the variety of biological activities and physicochemical characteristics. Due to the increasing demand for environmentally friendly synthetic methodologies, there has been considerable interest in the field of catalysis by iron‐based nanoparticles (Fe‐based NPs) along with green reaction media. This review gives a systematic outline of the current developments in the synthesis of imidazole and benzimidazole derivatives using Fe‐based nanoparticles and in environmentally friendly solvents such as water, ethanol, and polyethylene glycol (PEG). The reported methods involved one‐pot multicomponent condensation reactions of aldehydes, 1,2‐diketones, or α‐hydroxy ketones with ammonium acetate, amines, or o‐phenylenediamine using Fe ₃ O ₄ ‐encapsulated magnetic nanocrystals, Fe‐based nanocomposites, supported Fe nanoparticles, and bio‐derived nano Fe as catalysts. The review critically compares reaction conditions, scope, catalytic efficiency, product yields, and reaction times. The studies reported in the literature reveal that Fe‐based nanocatalysts are capable of providing structurally varied imidazole derivatives in excellent yields (usually 75%–99%) at mild reaction conditions with remarkably short reaction times in green solvents. The catalysts are found to be very stable over 5–10 consecutive recycling cycles, with almost negligible metal leaching, demonstrating their practical sustainability with almost negligible metal leaching, demonstrating the practical sustainability of the catalysts.