STUDIES ON ELECTRON IMPACT-INDUCED FRAGMENTATION OF NITROBENZENE AND NITROSOBENZENE MOLECULAR-IONS

The pathways of fragmentation of electron impact-excited molecular ion s of o- and p-dinitrobenzenes, o- and p-iodonitrobenzenes, and p-dinit rosobenzene were studied by field defocusing. The first stage in the f ragmentation of the molecular ions of o- and p-dinitrobenzenes is an o xygen atom or a nitro group splitting off. The nitro-nitrite rearrange ment of these compounds is only observed at the stage of formation of the nitrobenzene ion-radical. For iodonitrobenzene isomers, the nitro- nitrite rearrangement is observed at a first act of electron impact (E I)-induced fragmentation. Nitrogen-atom elimination is found to be one of the fragmentation routes of a p-dinitrobenzene ion.