Étude de la Décarbonylation du 1‐Acétylimidazole et du 1‐Acétylpyrazole Ionises

Collisionally activated dissociations (CAD) spectra have been used to investigate the structures of ions produced by decarbonylation of 1-acetylimidazole [1] and acetylpyrazole [12] ionized by electron impact. The results are best explained by the formation of non classical methylene-azolium ions. The loss of carbon dioxide from l-methoxycarbonylimidazole [7] does not produce these ions but instead leads to ionized C-methyl-2(or 4)H-imidazole. A mixture of structures is produced by electron impact induced fragmentation (loss of C2H4) of 1-(2-hydroxypropyl)imidazole [9]