Document Type and Number:
Japanese Patent JPS6225665
Kind Code:
B2
Abstract:
Process for the preparation of the monopotassium salt of 1,2,5-thiadiazol-3,4-dicarboxylic acid (I). Involves double-stage saponification of 3,4-dicyano-1,2,5-thiadiazole (II), 3-cyano-4-carbamoyl-1,2,5-thiadiazole (III) is obtained from an aqueous suspension of 3,4-dicyano-1,2,5-thiadiazole (II) by catalytic hydration through the addition of aqueous KOH, desirably at a temperature of from 20 DEG to 50 DEG C. and with a molar ratio of 3,4-dicyano-1,25-thiadiazole (II) to KOH of from 1:0.01 to 1:0.8. This is followed by hydrolysis, by the further addition of aqueous KOH, desirably at a temperature of from 85 DEG to 100 DEG C., until attaining an overall molar ratio of 3,4-dicyano-1,2,5-thiadiazole (II) to KOH of from about 1:2.0 to 1:2.35, a molar ratio of 3,4-dicyano-1,2,5-thiadiazole (II) to H2O of from about 1:20 to 1:23. Thereafter, from the resulting solution of dipotassium salt of 1,2,5-thiadiazole-3,4-diccarboxylic acid, the monopotassium salt is separated by acidification of said solution.
Inventors:
JIUSETSUPE RIBARUDONE
RENATO GUREKUU
RENATO GUREKUU
Application Number:
JP2873277A
Publication Date:
June 04, 1987
Filing Date:
March 17, 1977
Export Citation:
Assignee:
MONTEDISON SPA
International Classes:
C07D285/10