Electron impact and chemical ionization mass spectra of nitro-substituted polyfunctional isomers

The electron impact and methane and ammonia chemical ionization mass spectra of some selected nitro-substituted isomeric benzalacetophenones, benzyl ketones and aromatic epoxides have been examined. The isomeric pairs show significant differences in the electron impact and chemical ionization spectra. The EI spectra show cleavage α to the carbonyl as the major fragmentation mode. Under CI conditions subtle differences in the fragmentation modes of isomeric pairs are more enhanced, and elimination reactions are more favoured in the o-nitro-substituted compounds than in the para isomers.