Pyridine-Containing schiff base derivatives for the struxtural determination of long-chain aldehydes by gas chromatography combined with mass spectrometry

Long-chain aldehydes, encountered as insect pheromones, were converted into Schiff bases with 3-aminopyridine, 3-(aminomethyl)pyridine, or 2-aminopyrimidine to provide derivatives suitable for revealing the alkyl chain structure by mass spectrometry. The two pyridine-containing derivatives were satisfactory in initiating a radical-induced cleavage. of the chain to give a series of fragment ions, the masses and relative abundance of which revealed the chain structure. The derivatives were applied to aldehydes having straight, branched (iso and anteiso), and unsaturated (delta-7, delta-9, delta-ll, and delta-13) structures; these all gave the fragmentation patterns that have been seen earlier for similar pyridine-containing derivatives of fatty acids (picolinyl esters) and alcohols (nicotinates).Of the two derivatives, those from 3-aminopyridine gave slightly simpler spectra. Derivatives formed from 2-aminopyrimidine were less satisfactory in revealing chain structure.