申请人:Montedison S.p.A.
公开号:US04077966A1
公开(公告)日:1978-03-07
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.degree. to 50.degree. 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.degree. to 100.degree. 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 H.sub.2 O 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.
制备1,2,5-噻二唑-3,4-二羧酸单钾盐(I)的过程包括对3,4-二氰基-1,2,5-噻二唑(II)进行双阶段皂化,通过加入水合KOH的水悬浮液,以3,4-二氰基-1,2,5-噻二唑(II)的摩尔比与KOH的摩尔比为1:0.01至1:0.8,最好在20℃至50℃的温度下进行催化水解,得到3-氰基-4-氨基甲酰基-1,2,5-噻二唑(III)。然后,通过进一步加入水合KOH,最好在85℃至100℃的温度下进行水解,直到3,4-二氰基-1,2,5-噻二唑(II)与KOH的总摩尔比为约1:2.0至1:2.35,3,4-二氰基-1,2,5-噻二唑(II)与H2O的摩尔比为约1:20至1:23。此后,通过酸化所得的1,2,5-噻二唑-3,4-二羧酸双钾盐的溶液分离出1,2,5-噻二唑-3,4-二羧酸单钾盐。