AbstractThe mass spectra of imidazole‐4(5)‐carboxaldehyde, its two 1‐methyl derivatives, 4(5)‐nitroimidazole, 5(4)‐nitroimidazole‐4(5)‐carboxaldehyde and 1‐methyl‐5‐nitroimidazole‐4‐carboxaldehyde are presented and discussed in comparison with those of other imidazole‐carboxaldehydes and nitroimidazoles earlier reported. The imidazole‐carboxaldehydes and their 1‐methyl derivatives exhibit the characteristic fragmentation of aromatic aldehydes, and differences between the isomers can be observed. The nitroimidazoles show the fragmentation typical of aromatic nitrocompounds. In the o‐nitroimidazole‐carboxaldehydes, the typical losses of aldehydes do not occur, but primary ortho effects between the formyl and nitro groups give rise to important fragmentation routes. In their 1‐methyl derivatives, the presence of the methyl group adjacent to the nitro group originates additional double and secondary ortho effects. For some of these transformations, fragmentation mechanisms are proposed.
Bochwic, Boleslaw; Frankowski, Andrzej; Kuswik, Gabriela, Polish Journal of Chemistry, 1981, vol. 55, # 5, p. 1055 - 1061