201-06-9Relevant articles and documents
Gas-Phase Synthesis of Triphenylene (C18H12)
Zhao, Long,Xu, Bo,Ablikim, Utuq,Lu, Wenchao,Ahmed, Musahid,Evseev, Mikhail M.,Bashkirov, Eugene K.,Azyazov, Valeriy N.,Howlader, A. Hasan,Wnuk, Stanislaw F.,Mebel, Alexander M.,Kaiser, Ralf I.
, p. 791 - 797 (2019)
For the last decades, the hydrogen-abstraction?acetylene-addition (HACA) mechanism has been widely invoked to rationalize the high-temperature synthesis of PAHs as detected in carbonaceous meteorites (CM) and proposed to exist in the interstellar medium (ISM). By unravelling the chemistry of the 9-phenanthrenyl radical ([C14H9].) with vinylacetylene (C4H4), we present the first compelling evidence of a barrier-less pathway leading to a prototype tetracyclic PAH – triphenylene (C18H12) – via an unconventional hydrogen abstraction–vinylacetylene addition (HAVA) mechanism operational at temperatures as low as 10 K. The barrier-less, exoergic nature of the reaction reveals HAVA as a versatile reaction mechanism that may drive molecular mass growth processes to PAHs and even two-dimensional, graphene-type nanostructures in cold environments in deep space thus leading to a better understanding of the carbon chemistry in our universe through the untangling of elementary reactions on the most fundamental level.
The ethyne-ethylidene rearrangement: Formation of indeno[2,1-α]indene and fluoranthene on flash vacuum pyrolysis of 1,4-diphenylbutadiyne
Brown,Eastwood,Wong
, p. 3607 - 3608 (1993)
Diphenylbutadiyne on flash vacuum pyrolysis at 1120√0.03 Torr gave a pyrolysate (22% mass recovery) consisting of the diyne (7%), indeno[2,1-a]indene (19%), fluoranthene (59%), acephenanthrylene (13%) and aceanthrylene (2%). It is proposed that indeno[1,2-a]indene is formed via 3-phenyl-1,2-didehydronaphthalene and fluoranthene via 1-phenyl-2,3-didehydronaphthalene.
Aryl-aryl bond formation by flash vacuum pyrolysis of benzannulated thiopyrans
Amick, Aaron W.,Wakamiya, Atsushi,Scott, Lawrence T.
, p. 5119 - 5122 (2008/12/20)
(Chemical Equation Presented) In contrast to fully unsaturated 7-membered ring sulfur heterocycles (thiepines), some of which extrude sulfur and give the ring-contracted hydrocarbon even at room temperature in solution, benzannulated thiopyrans (6-membere
Origin of Pyrene under High Temperature Conditions in the Gas Phase. The Pivotal Role of Phenanthrene
Sarobe, Martin,Jenneskens, Leonardus W.,Steggink, Ralph G. B.,Visser, Tom
, p. 3861 - 3866 (2007/10/03)
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.
