Abstract The method for coating Fe3O4 with V-doped TiO2 was presented. On the base of characterizing composition, morphology and properties, the prepared nano-sized Fe3O4@V/TiO2 composites were used as a heterogeneous photocatalyst to catalyze the synthesis of 2-substituted benzimidazoles under light. The photocatalyst Fe3O4@V/TiO2 composites showed the enhanced photocatalytic activity compared to no V-doped Fe3O4@TiO2, being able to yield various 2-substituted benzimidazoles in moderate to good yield with recyclability and stability. A possible photocatalysis mechanism was investigated. It was evident that holes, singlet oxygen and ∙O2̄ radical played important roles in the synthesis of 2-substituted benzimidazole. Moreover, some of the obtained products were proved to have excellent antibacterial activity.
Abstract An efficient and convenient synthesis of 2‐substituted benzimidazoles catalyzed by magnetic Fe 3 O 4 supported by modified bentonite (MB) was developed. Herein, a separable, magnetic catalyst Fe 3 O 4 /MB was successfully prepared on the basis of exploring Fe 3 O 4 synthesis by co‐precipitation method. Fe 3 O 4 was obtained in 96.09 % yield using sweet orange oil as a reducing and protecting agent. The result showed that the sweet orange oil played a crucial role in the preparation of Fe 3 O 4 . Fe 3 O 4 and Fe 3 O 4 /MB were characterized by powder XRD, SEM, EDX, XPS and BET, and were further applied to catalyze the synthesis of 2‐substituted benzimidazoles. The applicability of the substrate was investigated on the basis of optimizing the reaction conditions. As a consequence, 2‐substituted benzimidazoles were obtained in 37.01–91.68 % yield. It suggested that Fe 3 O 4 /MB was an environmentally friendly and low‐cost catalyst possessing good catalytic activity, broader substrate adaptability and excellent recyclability. It is a promising catalyst in industrial production.
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