ZrOCl2.8H2O@nano SiO2: a green and recyclable catalyst for the synthesis of benzimidazoles

ZrOCl2.8H2O@nano SiO2 has been synthesized for the first time via a simple procedure and characterized by SEM (scanning electron microscopy), FT-IR, and EDX (energy-dispersive X-ray) techniques. The efficiency of the prepared nanostructure has been explored for the synthesis of benzimidazoles via the condensation reaction of orthoesters and diamines at 60 °C under solvent-free conditions. The successful synthesis of benzoxazole has also been explored through the condensation of orthoesters with 2-aminophenol in water media at room temperature. The recovery and reusability of the nanocatalyst has also been examined via 4 runs without activity loss. Partial short reaction times, high yields of products, mild reaction conditions in the absence of any hazardous solvent, and reusability of the nanocatalyst are noteworthy advantages of this method.