Hydrochloric Acid → 3-Thiophenecarboxylic acid, 4-(aminosulfonyl)-

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Reaction Steps

Preparation is according to the method disclosed in U.S. Pat. No. 4,028,373. A solution of 0.5 g. of 4-(aminosulfonyl)-3-thiophenecarboxylic acid methyl ester in 20 ml. of 10% aqueous sodium hydroxide is allowed to sit at room temperature for 3 days. The solution is acidified with concentrated hydrochloric acid. The precipitate which forms is collected to give 0.35 g. of product. A small amount is recrystallized twice from ethyl acetate (petroleum ether is added to the cloudy point to initiate precipitation) to give the analytical sample, m.p. 222°-224° C.

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