A. Necula et Lt. Scott, High temperature behavior of alternant and nonalternant polycyclic aromatic hydrocarbons, J AN AP PYR, 54(1-2), 2000, pp. 65-87
Three different flash vacuum pyrolysis (FVP) set-ups were employed for the
study of the thermal behavior of alternant and nonalternant polyclic aromat
ic hydrocarbons (PAH). The 1,2-switch of carbon atoms in the thermal autome
rizations of PAH, previously observed in benzene, pyrene and benz[a]anthrac
ene, has been additionally observed for [1-C-13]anthracene, [6-C-13]benzo[c
]phenanthrene and [1-C-13]- and [4-C-13]phenanthrenes at temperatures betwe
en 900 and 1100 degrees C. Bay region PAH (chrysene, benz[a]anthracene, phe
nanthrene, picene, perylene, benzo[ghi]perylene, benzo[e]pyrene, and benz[a
,c]-anthracene) were discovered to undergo an intriguing transformation whe
n heated at 1100 degrees C; the transformation is believed to be triggered
by cyclodehydrogenation across the bay region. Thermal formation of five-me
mbered rings was used to synthesize a series of new nonalternant hydrocarbo
ns. When the thermal closure of a five-membered ring is energetically unfav
orable, migration of an ethynyl group from one benzene ring to another alon
g the edge of a PAH (e.g. anthracene) can take place. (C) 2000 Published by
Elsevier Science B.V.