Mechanistic pathways of various phenylene rearrangements, observed in flash vacuum pyrolysis (FVP) studies, have been studied computationally. Specifically, Vollhardt's report of the isomerization of angular [4]phenylene to a biphenylene dimer is of interest.[1] A benzene ring contraction route involving carbene intermediates was compared to a diradical pathway -- proposed by Vollhardt -- to determine the most likely route. The results illustrated that the mechanism involving 1,2-hydrogen shifts and 1,2-carbon shifts is unlikely, compared to the diradical pathway. Moreover, Vollhardt also found that FVP of biphenylene dimer eventually gives rise to coronene. This particular pathway is of interest as it involves 1,2-carbon shifts without simultaneous hydrogen shifts. Results on the mechanism leading to coronene will be reported.[1] Dosa, P. I.; Gu, Z.; Hager, D.; Karney, W. L.; Vollhardt, K. P. C.  Chem. Commun. 2009 , 1967-1969.

Computational study of high-temperature rearrangements of phenylenes

245th National Meeting (2013)

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