The Pyrolysis of ωω'-Diphenylalkanes

The pyrolysis of several ωω'-diphenylalkanes, C6H5(CH2)nC6H5, where n=1, 2, 3, 4, and 6, has been studied over a range of temperatures (550, 600, 650, and 700 �C). The products were analysed by a combination of gas-liquid chromatography, chromatography on alumina, and partition chromatography on acetylated cellulose. Below 700 �C, scission of the aliphatic carbon bonds was solely observed, whereas at 700 �C there were formed, in addition, polycyclic aromatic hydrocarbons arising from radical processes such as dimerization, intramolecular cyclization, and homolytic aromatic substitution (e.g. phenanthrene, chrysene, triphenylene, and 3,4-benzpyrene). The mode of formation of these and other products is discussed.