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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Computational Study of the Oxygen Initiated Decomposition of 2-Oxepinoxy Radical:A Key Intermediate in the Oxidation of Benzene
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Computational Study of the Oxygen Initiated Decomposition of 2-Oxepinoxy Radical:A Key Intermediate in the Oxidation of Benzene

机译：2-氧代氧代氧基自由基的氧引发分解的计算研究：苯氧化的关键中间体

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Density functional theory was utilized to determine whether the addition of O_2(~3SIGMA_g) to 2-oxepinoxy radical,a proposed intermediate in the unimolecular decomposition of phenylperoxy radical,followed by unimolecular rearrangement and decomposition results in the formation of experimentally detected C_1-C_5 products via oxidative combustion of benzene.B3LYP/6-31G geometries for possible pathways resulting from the initial formation of 1,2-dioxetanyl,1,3-peroxy,1,4-peroxy,hydroperoxy,and peroxy moiety scission intermediates were calculated.Energies were determined by B3LYP/6-311+G single-point energy calculations on the B3LYP/6-31G geometries.For the O_2 addition steps and most favored pathway,the B3LYP/6-31G geometries were reoptimized and energies obtained via the CBS-QB3 method.The B3LYP/6-31G geometries were also used to obtain the energetic parameters to generate the free energy profiles for all pathways at 298,500,750,1000,and 1250 K.For temperatures between 298 and 750 K,the formation of peroxyoxepinone radicals and their decomposition pathways and products are competitive with those proposed by Fadden for the unimolecular decomposition of 2-oxepinoxy radical.However,a large entropic penalty,associated with the step for O2 addition to 2-oxepinoxy radical,is incurred at higher temperatures,thereby making these pathways less competitive as the temperature rises.At temperatures <1250 K,the same pathway maintains the lowest overall free energy profile and corresponds to rearrangement of 6-peroxyoxepinone (1c) to form a 1,4-peroxy intermediate between the ring carbons adjacent to the ester moiety (15a),followed by release of CO_2 to form 5-oxapentenal radical (21c),which then cyclizes (22c) and releases formyl radical,thereby generating furan,CO_2,and formyl radical as final products (10a).At 1250 K,all pathways proceeding from 2-peroxyoxepinone (la) and through the peroxy bond scission intermediate (16a) have the lowest free energy profile.
机译：利用密度泛函理论确定O_2（〜3SIGMA_g）是否加到2-氧杂环戊氧基中，这是苯过氧自由基单分子分解的拟议中间体，随后单分子重排和分解导致形成实验检测到的C_1-C_5产物通过苯的氧化燃烧，计算了B3LYP / 6-31G的几何构型，用于初步形成1,2-二氧杂环丁烷基，1,3-过氧，1,4-过氧，氢过氧和过氧部分分裂中间体的可能途径。通过对B3LYP / 6-31G几何结构进行B3LYP / 6-311 + G单点能量计算来确定。对于O_2添加步骤和最有利的途径，重新优化了B3LYP / 6-31G几何结构，并通过CBS-获得了能量QB3方法。还使用B3LYP / 6-31G几何形状来获取能量参数，以生成298,500,750,1000和1250 K时所有路径的自由能曲线。对于298至750 K之间的温度，过氧氧戊环酮自由基的形成及其分解途径和产物与Fadden提出的2氧环己氧基自由基的单分子分解具有竞争性。但是，在20℃时会产生较大的熵损失，这与O2加成2-氧氧杂环戊氧基自由基的步骤有关。较高的温度，从而使这些途径在温度升高时竞争性降低。在温度<1250 K时，同一途径保持最低的总自由能分布，并对应于6-peroxyoxepinone（1c）的重排以形成1,4-peroxy中间体在与酯部分（15a）相邻的环碳之间形成环氧基，然后释放CO_2形成5-氧杂戊烯醛自由基（21c），然后环化（22c）并释放甲酰基，从而最终生成呋喃，CO_2和甲酰基产物（10a）。在1250 K时，从2-过氧氧皮酮（1a）到过氧键断裂中间体（16a）的所有路径的自由能分布最低。

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