Electron impact studies. LXXVII. The question of scrambling in arylpyridine molecular ions

Abstract

The loss of a phenyl radical from the molecular ion of 2,4,6- triphenylpyridine is a slow process which occurs mainly from the 2- position with a minimum of scrambling of the pyridine carbon atoms or migration of the phenyl groups. The spectra of ²H, ¹³C, and F labelled derivatives demonstrate that no phenyl/pyridine carbon scrambling occurs during this process, that fluorine scrambling does not occur between the phenyl residues, but that considerable hydrogen scrambling precedes or accompanies fragmentation. The loss of HCN from the [M- Ph^.]⁺ ion of 2,4,6-triphenylpyridine occurs in a specific manner, showing that the original pyridine carbon atoms retain their positional identity during this elimination.