Studies in Mass Spectrometry. II. Random Hydrogen Rearrangement in Aromatic Molecular Ions

Abstract

To provide data for investigations by, inter alia, mass-spectrometric methods into the deuterium exchange of the aromatic hydrogen of some coal fractions, a study was made which confirmed the occurrence of completely random hydrogen rearrangement prior to or during the elimination of C₂H₂ in the molecular ions of benzene-1,2,3-d₃, benzene-l,3,5-d₃, naphthalene-1,2,3,4-d₄, naphthalene-1,4,5,8-d₄, and phenanthrene-9,10-d₂, and in the phenyl ions derived from o-bromobenzene-d, m-bromobenzene-d, and p-chlorobenzene-d, Similar but incomplete hydrogen rearrangement was found to occur in the molecular ion of carbazole-N-d prior to or during elimination of HCN. Such rearrangements, for which mechanistic considerations are presented, must be taken into account when the mass spectra of deuterium-substituted aromatic compounds are being interpreted.