Mass spectrometric behaviour of 4-(arylimino)pentan-2-ones substituted with a halogen atom in the aromatic ring

Investigation of 4-(Nitrophenylamino)Pent-3-En-2-Ones and 4-(Nitrobenzylamino)Pent-3-en-2-Ones by Electron Ionization Mass Spectrometry. Observation of Characteristic Ortho Effects

“…The EI mass spectra, metastable ion spectra and high resolution data were recorded on an AMD 402 two-sector mass spectrometer (AMD Intectra, Germany) as described in detail elsewhere. [23][24][25] The elemental compositions of all ions agree with the fragmentation pathways of 1-6 discussed in this paper.…”

“…This is in very good agreement with the results of earlier research on EI-induced fragmentation pathways of this class of compounds that are N-substituted with different substituents. [23][24][25] The theoretical calculations ( Table 2) have shown that the radical cation of the tautomer b is the least stable, so that the tautomerisation a ® b after ionisation is unlikely. The EI spectra were recorded with different electron energies (60, 50, 40, 30 and 20 eV), but the fragmentation patterns observed were always like that obtained at 70 eV (Figure 3).…”