Pyrolytic Disintegration of Selected Tobacco Constituents and Pyrosynthetic Formation of Aromatic Hydrocarbons from Cleavage Products Formed by Pyrolysis

A rapid pyrolysis technique, combined with gas chromatographic separation and interpretation of mass spectra obtained from the resulting pyrolysispyrosynthesis products, has been used in the study of three different compounds present in processed tobacco: n-C₂₅ alkane, neophytadiene and phytol. The compounds are representative for a homologous series of n-alkanes and for a series of branched-chain compounds including neophytadiene, phytol, solanesol and esters of solanesol (tobacco constituents). At temperatures below 600°C the pyrolysis in the absence of oxygen, but in a helium flow gives only slight aromatisation when n-alkanes are treated. For the isoprenoid compounds neophytadiene and phytol aromatisation starts between 500 and 600°C. The products formed tend to develop more-condensed ring structures at increasing temperature, although benzene and toluene are dominating even at temperatures as high as 800 to 900°C. Aromatisation leading to relatively less methyl substitution results with increasing temperature. Previous pyrolysis work and recent interpretations point to the formation of structures such as acenaphthylene, acenaphthene, cyclopenta[cd]pyrene, 3,4-dihydrocyclopenta[cd]pyrene and probably similar structures derived from three and four-membered condensed ring structures produced.