Identification of aromatic alkynes and acyclic polyunsaturated hydrocarbons in the output of a jet-stirred combustor

As part of a study of the combustion of ethylene in a jet-stirred reactor, combustion products in the C/sub 4/-C/sub 12/ range were characterized by gas chromatography coupled with mass spectrometry and Fourier transform infrared spectrometry. Some components yielded equivocal mass spectra whose simple patterns appeared to indicate the presence of aromatic rings but whose molecular mass information ruled out such structures. Several others gave mass spectra similar to those of toluene and benzene, of benzene and toluene while still others gave mass spectra similar to those of toluene and benzene, but with molecular ions shifted 2 and 4 mass units lower. These data strongly suggest that many components were highly unsaturated acyclic molecules; however, the lack of structural detail in their mass spectra combined with the scarcity of reference compounds restricted the usefulness of the GC/MS data. The IR data confirmed the presence of acyclic benzene and toluene isomers and demonstrated the existence of other acyclic polyunsaturated hydrocarbons. A number of aromatic acetylene derivatives were identified as well. Many of the compounds found have been postulated as intermediates in theoretical models for the formation and growth of polycyclic aromatic compounds.