萘和茚的形成机理：从星际介质到燃烧火焰,The Journal of Physical Chemistry A

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萘和茚的形成机理：从星际介质到燃烧火焰
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2017-01-24 00:00:00 , DOI: 10.1021/acs.jpca.6b09735
Alexander M. Mebel ₁ , Alexander Landera ₂ , Ralf I. Kaiser ₃

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本文探讨了萘和茚的形成机理，它们代表带有两个六元环和一个五元加六元环的原型多环芳烃（PAH）。有关化学反应的理论研究从其势能面，速率常数和产物支化比的角度进行了概述。这些数据与交叉分子束和热解化学反应器中的实验测量结果进行了比较，分别模拟了星际介质（ISM）和类似燃烧环境中的极端条件。已表明潜在产生萘和茚的反应的结果严重依赖于温度和压力或碰撞能量，因此，在ISM，行星大气和燃烧火焰中，反应机理及其对PAH生长的贡献可能存在很大差异。不同的温度和压力。具体地，用关于苯基自由基与乙烯基乙炔的反应的速率常数和产物支化比的新的理论结果来说明该范例。萘及其衍生物的形成机理分析表明，在燃烧过程中，可以通过吸氢-乙炔加成（HACA）途径，环戊二烯基与自身以及与环戊二烯的重组，苄基与炔丙基的反应，茚基自由基的甲基化，以及苯基自由基与乙烯基乙炔和1,3-丁二烯的反应。在极端的地球化学条件下，萘和二氢萘可在碳中形成₆ H ₅ +乙烯基乙炔和C ₆ H ₅ + 1,3-丁二烯反应。乙炔基取代的萘可以通过乙炔基加成机理从苯（脱氢形式）或苯乙烯开始制备。燃烧中茚的形成机理包括：苯基自由基与C ₃ H ₄异构体丙二烯和丙炔的反应；苄基自由基与乙炔的反应；以及源自3-苯基丙烯的1-苯基烯丙基的单分子分解。 C ₆ H ₅ +丙烯反应，或来自C ₆ H ₅ + C ₃ H ₅。

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Formation Mechanisms of Naphthalene and Indene: From the Interstellar Medium to Combustion Flames

The article addresses the formation mechanisms of naphthalene and indene, which represent prototype polycyclic aromatic hydrocarbons (PAH) carrying two six-membered and one five- plus a six-membered ring. Theoretical studies of the relevant chemical reactions are overviewed in terms of their potential energy surfaces, rate constants, and product branching ratios; these data are compared with experimental measurements in crossed molecular beams and the pyrolytic chemical reactor emulating the extreme conditions in the interstellar medium (ISM) and the combustion-like environment, respectively. The outcome of the reactions potentially producing naphthalene and indene is shown to critically depend on temperature and pressure or collision energy and hence the reaction mechanisms and their contributions to the PAH growth can be rather different in the ISM, planetary atmospheres, and in combustion flames at different temperatures and pressures. Specifically, this paradigm is illustrated with new theoretical results for rate constants and product branching ratios for the reaction of phenyl radical with vinylacetylene. The analysis of the formation mechanisms of naphthalene and its derivatives shows that in combustion they can be produced via hydrogen-abstraction-acetylene-addition (HACA) routes, recombination of cyclopentadienyl radical with itself and with cyclopentadiene, the reaction of benzyl radical with propargyl, methylation of indenyl radical, and the reactions of phenyl radical with vinylacetylene and 1,3-butadiene. In extreme astrochemical conditions, naphthalene and dihydronaphthalene can be formed in the C₆H₅ + vinylacetylene and C₆H₅ + 1,3-butadiene reactions, respectively. Ethynyl-substituted naphthalenes can be produced via the ethynyl addition mechanism beginning with benzene (in dehydrogenated forms) or with styrene. The formation mechanisms of indene in combustion include the reactions of the phenyl radical with C₃H₄ isomers allene and propyne, reaction of the benzyl radical with acetylene, and unimolecular decomposition of the 1-phenylallyl radical originating from 3-phenylpropene, a product of the C₆H₅ + propene reaction, or from C₆H₅ + C₃H₅.

更新日期：2017-01-24

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