Hydrochloric Acid → Methylsulfamoylthiophene-3-carboxylic acid methyl ester

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Reaction Steps

12 g (50 mmol) of 2-chlorosulfonylthiophene-3-carboxylic acid methyl ester are dissolved in 120 ml of absolute chloroform. Thereupon, dry methylamine is conducted into the solution at room temperature until a moist pH paper shows an alkaline reaction with the solution. Thereafter, the mixture is stirred for a further 3 hours at room temperature, whereby a moist pH paper must give an alkaline reaction with the solution to the end. The mixture is poured into 100 ml of 2-N hydrochloric acid. The organic phase is separated and the aqueous phase is extracted with two 50 ml portions of chloroform. The combined organic phases are dried over sodium sulfate and evaporated to give an oil which crystallizes out upon cooling. There is obtained 2-N methylsulfamoylthiophene-3-carboxylic acid methyl ester of melting point 106°-107° C.

Provenance & Evidence