Isolation and ldentification of Aza-Arenes of Tobacco Smoke

The nitrogen analogues of polynuclear aromatic hydrocarbons (aza-arenes) were isolated and identified in a basic fraction of cigarette smoke condensate. Silicic acid chromatography removed the predominant nicotine alkaloids, while gel chromatography on Bio-Beads S-X12 in benzene effectively separated the aza-arenes from interfering aliphatic compounds. In addition, the gel columns separated the aza-arenes by ring number and degree of alkylation on the basis of an adsorption-type mechanism. These gel characteristics facilitated the identifications of a large number of isomeric aza-arenes. Compounds identified included 2-vinylpyridine, 3-vinylpyridine and 2-phenylpyridine as well as quinoline, isoquinoline, 4-azafluorene, benzoquinolines, benzoisoquinolines, 1-azafluoranthene, 7-azafluoranthene, 4-aza-pyrene, 7- azaindole, pyrroloquinoline and their mono-, di- and trimethyl derivatives. All eight possible isomers of benzoquinoline and benzoisoquinoline were found, four of which are being reported for the first time. Evidence was also found for the probable presence of 5,6-benzo-7-azaindole.