Antiparasitic nitroimidazoles. Part II. The decomposition of 5-nitro-2-(4-trans-styryl)-1-vinylimidazoles by sodium hydroxide

Abstract

trans-4-[2-(5-Nitro-1-vinylimidazol-2-yl)vinyl]benzoic acid (I) decomposes in alkaline solution to 4-carboxycinnamic acid, acetaldehyde, and acetylene. The rate of the reaction is of the first order in both the imidazole and the hydroxide ion concentration. In 50% aqueous dimethyl sulphoxide containing tetramethylammonium hydroxide, changes of the substituent in the styryl group exert little variation on the rate coefficient for decomposition, whilst changes in the 1-substituent induce significant reactivity variations. These results are interpreted as indicative of initial hydroxide attack at the 4-position, followed by rate-determining opening of the imidazole ring.