The Chemical Composition of a Coal-Tar Pitch

A coal-tar pitch has been analyzed by a variety of spectroscopic methods. The whole pitch was studied by elemental analysis, IR, 13C and 1H NMR as well as soft ionization MS techniques. The complex nature of the pitch was apparent from the MS studies and the “average” structure indicates that the pitch consists predominately of large highly condensed aromatic units with only about 10% of the possible aromatic sites substituted by alkyl groups, notably methyl groups. Chromatographic fractionation followed by GC/MS and fluorescence spectroscopy allowed a number of individual lower molecular weight components to be identified, while more general information on the fractions was obtained by elemental analysis, 1H NMR and CI/MS.