Mass spectrometry of diaziridines: 1—Rearrangements of the molecular ion of 1-benzyl-3,3-dimethyldiaziridine and identification of some daughter ions using collisional activation

Intense rearrangement processes involving migrations of hydrogen atoms and the phenyl group were observed in the electron impact induced fragmentation of 1-benzyl-3,3-dimethyldiaziridine. The following ions are observed: (i) m/z 146: a two-step fragmentation involving hydrogen transfer followed by loss of NH₂; (ii) m/z 119: C—N¹ bond fission followed by a 1–4 phenyl shift and loss of CH₃N₂; (iii) m/z 106: a process involving reciprocal hydrogen migration between the methyl and benzylic methylene groups; (iv) m/z 58: hydrogen transfer from benzylic methylene and subsequent loss of PhCHN. The origin of these ions has been confirmed by measurements of metastable transitions in 1-benzyl-3,3-dimethyldiaziridine, and on specifically deuterated and substituted diaziridines. The structure of the ions at m/z 119 and m/z 106 has been deduced by means of collisional activation spectrometry.