Pyrolysis studies on model aromatic sulfur compounds

The incorporation of sulfur into pitches made from dinaphthylenethiophene, dibenzyldisulfide and dibenzothiophene, and the subsequent elimination of sulfur during carbonization were studied. Strained fivemembered rings in the dinaphthalenethiophene system were shown to lead to facile removal of sulfur. The ease of sulfur elimination during the conversion of dibenzyldisulfide into pitch shows the relative instability of sulfur in aliphatic side chains substituted on aromatic rings. The sulfur in dibenzothiophene is stabilized in large polymeric structures which eliminate sulfur only at high temperatures.