Vapor phase photochemistry of methylpyridines

Abstract

Irradiation of any one of the methylpyridine isomers 2, 3 , or 4 in the vapor phase at 254 nm results in the formation of the other two. These interconversions are consistent with a mechanism involving 2,6-bonding, nitrogen migration, and re-aromatization. In order to gain further mechanistic information, 2-trideuteriomethylpyridine-4,6-d[subscript 2] (2-4,6-d2), 3-methylpyridine-2,6-d[subscript 2](3-2,6-d2), and 4-trideuteriomethyl-pyridine-2,6-d[subscript 2] (4-2,6-d2) were synthesized and their photochemistry studied in the vapor phase. The photoreactions were carried out with appropriate light sources and analyzed by [superscript 1]H-NMR, GLC and GC-MS. The product identification was performed by the comparison of their chromatographic and mass spectroscopic data with the chemical shift of authentic methylpyridines.