Mass spectral rearrangements of acyclic dialkylnitrosamines: n-nitrosomethyl-n-butylamine and analogs.

Electron-impact mass spectra of N-nitrosomethyl-n-butylamine, 5 of its specifically deuterated anologs and its methyl-n-hexyl and methyl-n-octyl homologs have been examined. Hydrogen abstraction by the nitrosamino moiety dominates the rearrangement ions, especially at low ionization energy. All compounds exhibited the (M-OH)+ ion, for which the hydrogen abstraction is non-specific, involving the C-2 and C-3 positions in the methylbutyl homolog. In the same compound, the M-propene ion required the specific transfer of hydrogen from C-3. A double hydrogen migration was demonstrated for the formation of the m/z 61 ion, CH5N2O+, corresponding to a protonated diazotic acid. A skeletal rearrangement is indicated by the ion C4H9O+. The new information should prove helpful in structure studies of this class of compounds.