Green synthesis of novel azo-linked 2-phenyl benzimidazoles using ionic liquid [BDBDMIm]Br

•Novel azo-linked benzimidazoles were synthesized.•New method consist of using ionic liquid was carried out.•All of synthesized compounds were characterized by IR, NMR and elemental analysis.•This method provides simple work-up and environmental friendliness.•And shorter reaction time along with high yields.

Benzimidazoles can serve as unique and versatile scaffolds for experimental drug design. Since, a wide range of methods are available for synthesizing benzimidazole nucleus and its derivatives but a real need exists for new procedures that support many kinds of structural diversity and various substitution. In this research, novel series of benzimidazoles were synthesized using the reaction between various synthetized salicylaldehydes, and naphthalene-2,3-diamine or 1,2-diaminobenzene in the presence of a catalytic amount of 3,3-(butane-1,4-diyl)bis(1,2-dimethyl-1H-imidazole-3-ium)Br by a one-pot procedure without additional organic solvents and oxidants. IR, 1H NMR and 13C NMR spectroscopy and elemental analysis were used for the identification of these compounds.