Synthetic process of fexofenadine hydrochloride

The invention discloses a synthetic process of fexofenadine hydrochloride. The synthetic process of fexofenadine hydrochloride comprises the following steps of: with alpha, alpha-dimethyl phenylacetic acid as a raw material, carrying out an esterification reaction on alpha, alpha-dimethyl phenylacetic acid and absolute ethyl alcohol under the catalysis of a silica gel loaded phosphotungstic acid (PW12/SiO2) solid acid catalyst to obtain alpha, alpha-dimethyl ethyl phenylacetate; carrying out Friedel-Grafts reaction on alpha, alpha-dimethyl ethyl phenylacetate and 4-chlorobutyryl chloride to obtain alpha, alpha-dimethyl-4-(4-chloro-1-oxo butyl) ethyl phenylacetate; reducing by virtue of sodium borohydride in 95% ethyl alcohol to obtain alpha, alpha-dimethyl-4-(4-chloro-1-hydroxyl butyl) ethyl phenylacetate; and carrying out N-alkylation reaction on alpha, alpha-dimethyl-4-(4-chloro-1-hydroxyl butyl) ethyl phenylacetate and alpha, alpha-dimethyl-4-piperidine methyl alcohol in DMF (dimethyl formamide) for 24 hou