Study of the mass spectral fragmentation processes in dinitroquinoxalines using tandem methodologies

Following electron ionization, the fragmentations of isomeric dinitroquinoxalines have been investigated making use of tandem mass spectrometry methodologies such as collisional activation (CA), various linked-scanning (LS) experiments, and mass-analyzed ion kinetic energy (MIKE) spectrometry. It was shown that, for the two ortho-dinitroquinoxalines 1 and 2, the most abundant fragment ion at m/z 116 is generated for 1 by successive losses of NO2•, CO, and NO•, whereas for 2, it is the result of two main competing fragmentation routes. The fragmentation of the meta-dinitroquinoxaline 3 differs significantly as an abundant and quite characteristic ion at m/z 127 is the result of consecutive eliminations of NO2• and HNO2. Substitution of the pyrazine ring (for example, compounds 4 and 5) or of the benzene ring (for example, compounds 6 and 7) strongly modifies the reactivity.SCOPUS: ar.j