GB769757A - Improvements in or relating to the manufacture of sulfonamides - Google Patents

Abstract

2 - Acylamino - 1,3,4 - thiadiazole - 5 - sulphonamides of the general formula <FORM:0769757/IV(b)/1> wherein R1 is an acyl radical and R2 is then hydrogen, and when R1 and R2 are taken together they form the phthaloyl radical, are prepared by reacting 2-amino-1,3,4-thiadiazole-5-sulphonamide with the required carboxylic acid anhydride or acyl chloride. In the case of the anhydride reactants, the process may be carried out in the absence of solvents, a suitable reaction temperature using an anhydride reactant being 100 DEG to 200 DEG C., preferably 140 DEG to 180 DEG C. In the case of the acyl chloride reactants, the process is preferably carried out in the presence of an acid acceptor, e.g. pyridine, quinoline, triethylamine, tripropylamine or other tertiary aliphatic amine, or an inorganic base such as an alkali metal hydroxide, carbonate or bicarbonate. The group R1 may be a lower alkyl carbonyl radical such as a propionyl, acetyl, trifluoroacetyl, butyryl, isobutytyl, chloroacetyl, aminoacetyl, valeryl, or isovaleryl radical, or an aroyl radical such as the benzoyl radical. In the examples, the following compounds are prepared: 2-propionyl-, 2-acetylamino-, 2-trifluoroacetylamino-, 2-phthaloylamino-, 2-n-butyrylamino-, 2-chloroacetylamino-, 2-isovalerylamino-, 2-benzoylamino-, 2-isobutyrylamino-, and 2-[(N-carbobenzoxy) glycylamino] - 1,3,4 - thiadiazole - 5 - sulphonamide. Specification 687,760 is referred to.