Ethanol → 5,6-Dichloro-2-(4-carboxy-2-ethoxyphenyl)benzimidazole hydrochloride

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Reaction Steps

A mixture of 5,6-dichloro-2-(4-cyano-2-ethoxyphenyl)benzimidazole hydrochloride (16.3 g, 44.2 mmol), prepared as in Preparation 12, 32% NaOH (40 ml) in ethanol (100 ml) was refluxed for 8 h. After cooling to room temperature the organic solvent was removed under vacuum and the aqueous phase was acidified with 37% HCl, stirred for 1 h. The solid was filtered, washed with water (100 ml) and dried at 50° C. under vacuum to give 12 g of the title compound as a light brown powder (yield 70%), mp>250° C.

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