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

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Eur. J. Mass Spectrom. 5, 59 - 67 (1999)

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

Sylvie Heilporn^* and Michel Kaisin
Service de Chimie Organique, Université Libre de Bruxelles, CP 160-06, Avenue F.D. Roosevelt 50, B-1050 Bruxelles, Belgium.
Ulrich Boesl
Technische Universität München, Institut für Physikalische und Theoretische Chemie, D-85747 Garching, .
Robert Flammang
Service de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium.

ABSTRACT:

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.

Keywords: Tandem mass spectrometry, linked scan experiments, CID-MIKES, fragmentation pathways, rearrangement, dinitroquinoxaline derivatives

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