Anomalous side-chain cleavage in alkylaromatic thermolysis

In reactions of hydrocarbons, alkylaromatic side chain cleavage occurs as the result of thermal or acid catalyzed cracking chemistry. In general, acid catalysis leads to direct bond cleavage at the aromatic ring whereas thermally promoted bond breaking gives primarily substituted aromatics. The formation of a core aromatic by a thermal process is expected only at higher temperatures and in low yield due to the need for hydrogen atoms. Recently, for the alkylpyrene system, extensive direct side chain cleavage has been observed for liquid phase, low temperature (375-425{degree}C) pyrolysis (43% yield of pyrene at 400{degree}C and 180 min.). Pyrene formation was reported to be the result of autocatalysis. This yield of core aromatic is much greater than that found for single ring aromatics. In this paper, the authors with to report the results of a combined theoretical and experimental study which they believe does provide experimental confirmation of a direct cleavage path. In support of this conclusion, they present an analysis of the possible reaction pathways.