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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetics of Intramolecular Phenyl Migration and Fused Ring Formation in Hexylbenzene Radicals
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Kinetics of Intramolecular Phenyl Migration and Fused Ring Formation in Hexylbenzene Radicals

机译：分子内苯基迁移的动力学和己苯基苯乙烯基的稠合环形成

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A combined ab initio/TST study was conducted to study the phenyl migration and fused ring formation of a series of 1-phenyl-hex-x-yl radicals. Phenyl shift proceeds through a two-step mechanism with a ring closure by ipso-cycloaddition, followed by a ring-opening by beta-scission leading to x-phenyl-hex-1-yl radical isomers. Both steps involve a spirocyclic transition state connected by a spirocyclic intermediate. Barrier heights at the CBS-QB3 level range from 9.9 to 17.7 kcal mol(-1) depending on the size of the newly formed ring. Formation of fused rings by peri-cycloaddition reactions occur through barrier heights that range from 8.8 to 28.8 kcal mol(-1). The addition sites are the substituted and ortho carbons of the phenyl ring for the ipso- and peri-cycloadditions, respectively. For both types of reaction, the Arrhenius A factor decreases as the ring size increases. This is related to the number reaction. In addition, length of the side chain also impacts on the kinetics as longer side chains decrease the barrier height required to form a second cycle. Electrons in the cyclohexadienyl group of the spiro and fused rings are much more localized than expected, with the presence of two distinct It bonds. Rate coefficients for each reaction are provided. The unimolecular reactions are fast at most conditions, implying that ring formation and/or ring-opening processes will equilibrate 1-phenyl-hex-x-yl and x-phenyl-hex-1-yl radicals and the Spiro and fused isomers.
机译：进行了组合的AB InitiO / TST研究以研究苯基迁移和熔融环形成一系列1-苯基 - 六己-X-YL基团。苯基换档通过具有IPSO-环绕编辑的环形封闭的两步机构进行，然后通过β-易分裂的环开口，导致X-苯基 - 十六烯-1-基自由基异构体。这两个步骤都涉及通过螺环中间体连接的螺环过渡状态。 CBS-QB3级别的屏障高度范围为9.9至17.7千克Mol（-1），这取决于新形成的环的尺寸。通过Peri-环绕反应形成融合环，通过屏障高度发生，范围为8.8至28.8 kcal mol（-1）。添加位点分别是苯环的取代和邻碳，用于IPSO和Peri-环绕着。对于两种类型的反应，由于环尺寸的增加，Arrhenius A因子降低。这与数字反应有关。另外，侧链的长度也影响动力学，因为较长的侧链会降低形成第二循环所需的屏障高度。螺旋和熔环的环己二烯基的电子比预期的更为局限性，存在两个不同的IT键。提供每种反应的速率系数。单分子反应在大多数条件下快速，暗示环形形成和/或开环过程将平衡1-苯基 - 六己-X-Y1和X-苯基 - 十六烯-1-基的基团和螺旋和熔融异构体。

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