Benzazoles such as benzimidazoles are considered as important class of heterocyclic compounds possessing interesting biological and pharmacological properties as anti-fungal, anti-oxidant, anti-inflammatory, anti-bacterial, anti-viral and anti-cancer agents 1. The most attractive method for the synthesis of benzimidazoles2 is the reaction of 1,2-phenelynediamine with aldehydes 3. Recently reported methods mostly employed homogeneous catalysts which require special work-up and separation technique for the recovery and recycling form the reaction environment. Following our studies in this field4 .In this research, Fe3O4@SiO2@COOH as a new, high efficient and green solid acid catalyst has been prepared and used for the synthesis of benzimidazoles under solvent free conditions. The recovery and reuse of a catalyst is highly desirable during its practical application. We were able to recycle this catalyst five times and use it in reaction, without reducing the efficiency of the product.
