Phenyl-substituted polycyclic aromatic compounds as intermediate products during pyrolytic reactions involving coal tars, pitches and related materials

Summary Several so far unreported phenyl-substituted polycyclic, aromatic compounds were detected in coal tars, coal tar pitches and ring furnace flue gases by their gas chromatographic retention and mass spectra. In the case of thiophene-derived compounds, the elemental sulfur traces obtained by GC-AED supplied further evidence of their identity. Pure authentic substances were synthesised and analysed by GC-MS and GC-AED to prove the identity of the unknown compounds. Concentration profiles of phenyldibenzofurans and phenyldibenzothiophenes in different coal tars, coal tar pitches and ring furnace flue gases are reported. Reaction mechanisms are proposed which suggest that during oxidative pyrolysis phenyldibenzofurans and phenyldibenthiophene are the intermediate products on the path from dibenzofuran and dibenzothiophene to triphenyleno1,12-bcd]furan and benzobisbenzofurans, and the respective thiophenes.