The invention relates to an improved process for the preparation of 2,2-diphenyl-2-(2-ethylbutoxy)acetic acid 2-dimethylaminoethyl ester hydrochloride (DENAVERIN hydrochloride), which is used as the active compound of a human and veterinary pharmacon. According to the invention, benzilic acid or its alkali metal or alkaline earth metal salt is alkylated with dimethylaminoethyl chloride hydrochloride with the addition of tertiary, aliphatic or cycloaliphatic amines in aprotic, apolar solvents or the amines themselves, the resulting 2,2-diphenyl-2-hydroxyacetic acid 2-dimethylaminoethyl ester is converted into its hydrochloride, this is reacted by means of thionyl chloride to give 2,2-diphenyl-2-chloroacetic acid 2-dimethylaminoethyl ester hydrochloride, the latter is etherified with 2-ethylbutanol and in the presence of water-immiscible inert solvents boiling below 130 DEG C at temperatures from 120 to 132 DEG C to the final product, which is obtained in pharmaceutically pure form after recrystallisation from methyl ethyl ketone.
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