Mass spectra of nitrogen heterocycles. II. Pyridyl Schiff bases

Abstract

A number of anils of pyridine aldehydes and benzylideneaminopyridines were used to study positional effects of aromatic substituents and heteroatom placement on electron impact mass spectra. The simple fragmentation pattern of aromatic Schiff bases was obtained with all 3- and 4-pyridyl compounds when the other aromatic ring was unsubstituted phenyl, or in the case of anils, had a chloro or 3-methoxy substituent. Marked changes were brought about by a pyridyl ring at either end of the azomethine group when the heterocyclic nitrogen was adjacent to it. Displacement and rearrangement reactions then became dominant. Methoxy substitution para to the azomethine in all anils studied gave loss of methyl radical as the major reaction.