Chemical changes during the mild air oxidation of pitch

The chemical changes occurring during mild oxidation of petroleum and coal tar pitch were studied by elementary analysis, solubility measurements, IR and nuclear magnetic resonance spectroscopy and chromatography. The oxidized pitches were compared with pitches which were distilled to give similar softening points. A mild oxidation was shown to induce dehydrogenative polymerization of the pitch components without introducing appreciable amounts of oxygen into the products. The greater reactivity of the petroleum pitch constituents to oxygen is attributed to the presence of alkyl substituents. Study of the mesophase formation and X-ray analysis of the derived graphites showed that mild air oxidation did not affect the subsequent graphitic development.