Mass Spectral Studies on Pyrazaboles
2014
May, C. E. | Niedenzu, K. | Trofimenko, S.
The mass spectra of several pyrazaboles of type 1 (R = H) have been studied. The data illustrate that electron impact causes three major fragmentation patterns for the species. Symmetrical cleavage of the pyrazabole followed by further breakdown is common to all compounds. In addition, those pyrazaboles containing H or CH₃ at the C atoms of the pyrazole rings undergo an electron impact-induced rearrangement which appears to result in the formation of a species containing a B₂N₃ ring as a structural entity; subsequent breakdown leads to a B₂N₂ ring system. The mass spectra of halo- or pseudohalo-substituted pyrazaboles evidence the ready loss of hydrogen halide as a predominant feature; no rearrangement ions are observed.
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