Abstract: Emedastine difumarate(1) was prepared via improved synthetic processes. After adding phase transfer catalyst, the synthesis of the two key intermediates such as 2-chloro-1-(2-ethoxyethyl) benzimidazole(4) and emedastine(5) for the reactions could be optimized. No water was needed for the reactions and the yields were significantly enhanced. Typically, the yields of compounds 4 and 5 are up to 67.9% and 74.9%, respectively. The structure of the prepared product was confirmed by IR, 1H NMR, 13C NMR, MS, elemental analysis, differential thermal analysis, and X-ray powder diffraction.

Key words: Emedastine difumarate, synthesis, characterization, phase transfer catalysts