Pyrolysis of fulvenallene (C7H6) and fulvenallenyl (C7H5): Theoretical kinetics and experimental product detection

Fulvenallene and fulvenallenyl are the respective C7H6 and C7H5 global minima, yet their importance to combustion has only recently emerged. We have studied the pyrolysis of these species theoretically to obtain rate constants and compare our results to pyrolysis mass spectrometry experiments for product identification. Master equation modeling reveals that fulvenallene rapidly dissociates to fulvenallenyl + H, and that fulvenallenyl dissociates to form propargyl plus diacetylene, with lesser amounts of i-C5H3 (CH2CCCCH)/n-C5H3 (CHCCHCCH) plus acetylene. Photoionization mass spectrometry experiments using a pyrolysis source on the fulvenallene precursor phthalide identify products consistent with those proposed theoretically for both fulvenallene and fulvenallenyl decomposition.