Preparation, characterization, and application of 1,1'-disulfo-[2,2'-bipyridine]-1,1'-diium chloride ionic liquid as an efficient catalyst for the synthesis of benzimidazole derivatives

摘要

In this study, 2,2'-bipyridine was treated with chlorosulfonic acid and 1,1'-disulfo-[2,2'-bipyridine]-1,1'-diium chloride, [BiPy](SO3H)(2)Cl-2, as a new ionic liquid catalyst was obtained and characterized with a variety of techniques including IR, H-1, and C-13 NMR, Hammett acidity function as well as mass spectra method. After preparation and characterization, this ionic liquid was used as an efficient catalyst for the green and mild synthesis of benzimidazole derivatives. In addition, this reagent is efficiently able to catalyze the preparation of benzimidazole derivatives from the protected derivatives of aldehydes including oximes and semicarbazones. All reactions are performed under mild conditions in excellent yields.