%0 Journal Article
%A Sarobe, Martin
%A Jenneskens, Leonardus W.
%A Steggink, Ralph G. B.
%A Visser, Tom
%D 1999
%T Origin of Pyrene under High Temperature Conditions in the Gas
Phase. The Pivotal Role of Phenanthrene
%U https://acs.figshare.com/articles/journal_contribution/Origin_of_Pyrene_under_High_Temperature_Conditions_in_the_Gas_Phase_The_Pivotal_Role_of_Phenanthrene/3716493
%R 10.1021/jo982030e.s001
%2 https://acs.figshare.com/ndownloader/files/5808057
%K PAH
%K flash vacuum thermolysis
%K ratio
%K FVT
%K pyrene
%K insertion
%K formation
%K carbene
%K C 2 addition
%K High Temperature Conditions
%K chloroethenyl
%K ethynyl substituents
%K Phenanthrene
%X 4-Ethynylphenanthrene (15), and the latent precursors for 2-ethynyl- (18) and 3-ethynylphenanthrene (19), viz., 2-(1-chloroethenyl)- (16) and 3-(1-chloroethenyl)phenanthrene (17), respectively,
have been subjected to flash vacuum thermolysis (FVT). Whereas at 800 °C 15 is quantitatively
converted into pyrene (1), 16 and 17 only give 18 and 19, respectively. Both 18 and 19 contain
redundant ethynyl substituents, i.e., after ethynyl−ethylidene carbene equilibration neither five-
nor six-membered ring formation can occur by carbene C−H insertion. At T ≥ 1000 °C 16 and 17
gave pyrolysates containing the same set of 11 (non)-alternant polycyclic aromatic hydrocarbons
(PAH), albeit in a different ratio. The different product ratio suggests that redundant ethynyl
substituents migrate along the phenanthrene periphery presumably via transient cyclobuta-PAH
intermediates toward positions suitable for either five- or six-membered ring formation by carbene
C−H insertion. The results provide an explanation for the ubiquitous formation of pyrene (1),
acephenanthrylene (9), and fluoranthene (3) during (incomplete) combustion. Phenanthrene (2)
appears to be a point of divergence in PAH growth by C2 addition.
%I ACS Publications