Studies on the Composition of Tobacco Smoke Part XIV. Formation of Pyridines in Pyrolysis of Nicotine

Abstract

Nicotine and various pyridine homologues were pyrolyzed in the nitrogen and air atmosphere using an unpacked quartz tube as a reactor. 2- And 4-picolines and all kinds of isomers of lutidine were identified in the pyrolytic products of nicotine at 600~800°C besides 3-substituted pyridines and other products reported by earlier workers. Upon pyrolysis at 700~800°C, any kinds of picolines yielded all kinds of picoline isomers, lutidines, pyridine, quinoline, isoquinoline and 2, 2′-dipyridyl. Ethylpyridines and vinylpyridines being interconverted at 700~800°C, yielded mainly the corresponding picolines and pyridine. The yield ratio of quinoline to isoquinoline varied according to the substituted position of the ethylpyridines and vinylpyridines pyrolyzed. 3-Acetylpyridine was produced from 3-ethylpyridine in air atmosphere at 700°C. 3-Cyanopyridine was pyrolyzed at 800°C to yield low molecular weight compounds without pyridine nucleus. It seems to suggest that no intermediate pyridine compounds are involved in the pyrolysis. From these findings, the thermal degradation pathway of nicotine was proposed. It was concluded that the potential source of pyridines including pyridines other than 3-substitution in tobacco smoke is nicotine in tobacco leaf. © 1970, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.