Herbicide N-tert.-butyl-4,5-di:chloro-imidazole-2-carboxamide prodn. - by reaction of 3,4-di:chloro-2-di:chloro:methylene-imidazole with tert.-butylamine and reaction of resulting amidine with alkali hydroxide

摘要

In the prodn. of N-tert-butyl-4,5-dichloro-imidazole-2-carboxamide (I), (A) 4,5-dichloro-2-dichloromethyleneimidazole (II) is reacted with tert-butylamine (III) in the presence of an acid-binding agent and of diluent at -20 to +100 degrees C, and (B) the resulting N,N'-di-tert-butyl-4,5-dichloro-imidazole-2-carboxamidine (IV), without isolating, is reacted with alkali or alkaline earth hydroxide in the presence of water and of an additional diluent at 50-150 degrees C. The process gives (I) in very high yields and good purity. Starting materials are readily available. Simple one pot process gives reaction mixt. from which (I) can be isolated in crystalline form. Step (A) is pref. carried out at 0-50 degrees C using aqueous NaOH as acid binding agent. Step (B) is pref. carried out at 80-120 degrees C, and the alkali(ne earth) hydroxide is pref. NaOH or KOH. Dioxan is the preferred diluent.