To produce a new aminobenzenesulfonic acid derivative monohydrate useful for producing a medicinal composition effective in preventing or treating ischemic cardiopathy, cardiac failure and hypertension, etc.
This new aminobenzenesulfonic acid derivative monohydrate is represented by the formula [R1 is H, an alkyl, a halogen, etc.; R2 is H, an alkyl or cyano, an aralkyl, etc.; (n) is an integer of 1-4], e.g. 2-(1-piperazinyl)-5- methylbenzenesulfonic acid monohydrate. The compound represented by formula I is obtained by suspending an aminobenzenesulfonic acid derivative anhydride in water or a hydrous organic solvent or carrying out the crystallizing treatment of the dissolved solution and drying the formed crystal. The organic solvent to be used is a water-soluble organic solvent such as methanol or ethanol. The suspending treatment of the anhydride is preferably conducted by stirring the mixture at normal temperature for ≥2hr.
SATO TADAO
NAGANO TATSUO
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