OH. Loss and Molecular Rearrangements of Quinoxaline N-Oxides Studied by Interpretation of Mass Spectra and Application of Linear Discriminant Analysis

Article abstract of DOI:10.1002/oms.1210220507

Quinoxaline N-oxides substituted at the ortho position to the NO group give characteristic ⁺ fragments.With the di-N-oxides the peak intensities depend on the electron-withdrawing strength of the 2- and 3-substituents.Linear discriminant analysis was used to study the fragmentation of quinoxaline N-oxides as determined by the number of NO groups.Results of peak selection and discriminant analysis (Fisher quotients and discriminant vector coefficients) were interpreted with regard to the mass spectrometric decomposition of quinoxaline and quinoxaline N-oxide molecules.For the substituted quinoxaline N-oxides, fragmentations involving molecular rearrangements like those observed for unsubstituted quinoxaline N-oxides were also found.For these compounds, partial rearrangement to quinoxalines is confirmed.