Search

• The different nano-sized Fe 3 O 4 was prepared orange oil was used as a protective agent and the different surfactants was used as a dispersant by co-precipitation method. • The nano-sized Fe 3 O 4 @TiO 2 was prepared using HNO 3 as a hydrolysis inhibitor by sol-gel method under the optimal reaction condition. • 17 target products were synthesized using Fe 3 O 4 @TiO 2 as a photocatalyst in a 15 W incandescent lamp radiation under the optimum reaction condition. Also, the photocatalysis mechanism was studied by the aid of the action of different scavengers. • The effect of substituents on reaction time has been found to have good catalytic performance for substituents with smaller steric hindrance. • The recyclability of catalysts have been studied, and it was found that Fe 3 O 4 @TiO 2 had good catalytic activity, reusability and easy separation performance in the synthesis of 2-substituted benzimidazole. The method for immobilizing TiO 2 nanoparticles on Fe 3 O 4 was presented. On the base of microscopic and spectroscopic characterizations, the prepared Fe 3 O 4 @TiO 2 nanoparticle composites were employed as a heterogeneous photocatalyst to catalyze the synthesis of 2-substituted benzimidazoles under incandescent light. The composite material exhibited the enhanced photoactivity compared to bare TiO 2 and Fe 3 O 4 , being able to yield a variety of 2-substituted benzimidazoles in moderate to good yield with recyclability and stability. A possible photocatalysis mechanism was investigated based on the free radical scavengers tracking method. It was evident that holes, ·OH radical and singlet oxygen played the important roles in the synthesis of 2-substituted benzimidazole. Fe 3 O 4 @TiO 2 was prepared and applied to the photocatalytic synthesis of 2-substituted benzimidazole compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

An efficient and convenient synthesis of 2‐substituted benzimidazoles catalyzed by magnetic Fe3O4 supported by modified bentonite (MB) was developed. Herein, a separable, magnetic catalyst Fe3O4/MB was successfully prepared on the basis of exploring Fe3O4 synthesis by co‐precipitation method. Fe3O4 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 Fe3O4. Fe3O4 and Fe3O4/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 Fe3O4/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. [ABSTRACT FROM AUTHOR]

An efficient synthesis of 1,2,5-trisubstituted benzimidazoles was explored under microwave irradiation. Twenty novel 1,2,5-trisubstituted benzimidazoles were prepared using K2CO3 as an acid-binging agent starting from 2-substituted benzimidazoles and 4-substituted benzyl chloride. This method revealed broad substrate adaptability and provided the target products in moderate to excellent yield within 15 min. The effect of different substituents on the yield was investigated under the obtained optimal reaction conditions. Besides, the crystal structure of compound 4c in the orthorhombic space group P 2ac 2ab was presented. Also, the antibacterial activity of the synthesized compounds against Mycobacterium smegmatis in vitro at the cellular level was evaluated using rifampicin as a positive control. Product 4s had the best antibacterial activity among the synthesized compounds and was superior to rifampicin. [ABSTRACT FROM AUTHOR]