Mass spectrometry of the simple N ‐ vinylpyridinium salts

N ‐ Vinylpyridinium halides readily undergo a Hofmann type elimination, prior to evaporation in the mass spectrometer, with formation of pyridine, acetylene and hydrogen halide as volatile products. A second important reaction is thermally induced two electron reduction of the cation to the volatile N ‐vinyldihydropyridine. Of minor importance is the formation of volatile compounds with the elemental composition of [cation + C 2 H] and [cation + C 2 H 3 ]. The latter is suggested to have a divinyldihydropyridine structure. Its formation is explained as due to nucleophilic attack on the cation by the N ‐vinyldihydropyridine present with displacement of pyridine.