| 摘要 |
A method of preparing 3,3'-azo-bis-(6-hydroxy benzoic acid) of formula I <IMAGE> I and salts thereof in at least 98% purity for treating inflammatory intestinal diseases. According to the invention a compound II <IMAGE> II is diazotized, and the diazonium salt obtained is coupled with a compound III <IMAGE> III The formed intermediate IV, which is also comprised by the invention, <IMAGE> IV is hydrolized in alkaline medium to form the compound I. R1, R2 and R3 signify lower alkyl, R2 also possibly substituted phenyl. |
