V-Acetylimidazole

V-Acetylimidazole [2466-76-4] M 110.1, m 101.5-102.5°. Crystd from isopropenyl acetate. Dried in a vacuum over P2O5. 

Identified by Vitzthum and Werkhoff (1976b), who synthesized it for the first time by treating 2-methylpyrrole (K.3) with (V-acetylimidazole and confirmed the structure by NMR spectroscopy. An MS fragmentation pathway is proposed. 

The imidazole-catalysed hydrolysis of polar substituted 2,4-dinitrophenyl acetates (21 X = Cl, OMe) has been investigated at different temperatures. The observed rates correspond to the bimolecular nucleophilic addition of the imidazole at the carboxylic carbon atom followed by a very fast hydrolysis of the (V-acetylimidazole in water. The influence of polar substituents in the acid moiety of the ester molecule on the hydrolysis reaction can be described by an electrostatic dipole-dipole interaction in the same way as the neutral hydrolysis of polar substituted ethyl acetates. By the use of both quantum and classical dynamics, a study of the neutral hydrolysis of 4-methoxyphenyl dichloroacetate (22) in water concluded that the rate-determining step is a proton transfer concerted with formation of a C-O bond. ... 

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