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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Computational Kinetics of Hydroperoxybutylperoxy Isomerizations and Decompositions: A Study of the Effect of Hydrogen Bonding
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Computational Kinetics of Hydroperoxybutylperoxy Isomerizations and Decompositions: A Study of the Effect of Hydrogen Bonding

机译：氢过氧基二乙烯基异氧基异构化和分解的计算动力学：氢键粘合作用的研究

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摘要

Hydroperoxyalkylperoxy (OOQOOH) radicals are important intermediates in combustion chemistry. The conventional isomerization of OOQOOH radicals to form ketohydroperoxides has been long believed to be the most important chain branching reaction under the low-temperature combustion conditions. In this work, the kinetics of competing pathways (alternative isomerization, concerted elimination, and H-exchange pathways) to the conventional isomerization of different beta-, gamma- and Delta-OOQOOH butane isomers are investigated. Six- and seven -membered ring conventional isomerizations are found to be the dominant pathways, whereas alternative isomerizations are more important than conventional isomerization, when the latter proceeded via a more strained transition state ring. The oxygen atoms in OOQOOH radicals introduce intramolecular hydrogen bonding (HB) that significantly affects the energies of reacting species and transition states, ultimately influencing chemical kinetics. Conceptually, HB has a dual effect on the stability of chemical species, the first being the stabilizing effect of the actual intramolecular HB force, and the second being the destabilizing effect of ring strain imposed by the HB conformer. The overall effect can be quantified by determining the difference between the minimum energy conformers of a chemical species or transition state that have HB and that do not have HB (non-hydrogen bonding (NHB)). The stabilization effect of HB on the species and transition sates is assessed, and its effect on the calculated rate constants is also considered. Our results show that, for most species and transition states, HB stabilizes their energies by as much as 2.5 kcal/mol. However, NHB conformers are found to be more stable by up to 2.7 kcal/mol for a few of the considered species. To study the effect of HB on rate constants, reactions are categorized into two groups (groups one and two) based on the structural similarity of the minimum energy conformers
机译：氢过氧羰基氧基（OOQOOH）基团是燃烧化学中的重要中间体。常规异构化OOQOOH自由基形成酮氢氧化酯，已被认为是低温燃烧条件下最重要的链支化反应。在这项工作中，研究了竞争途径的动力学（替代异构化，齐全的消除和H-交换途径）对不同β，γ-和Δ-oOQoOh丁烷异构体的常规异构化的常规异构化。发现六个和七元的环常规异构化是主要的途径，而当后者通过更紧张的过渡状态环进行时，替代的异构化比常规异构化更重要。 OOQOOH基团中的氧原子引入分子内氢键（HB），其显着影响反应物种和过渡状态的能量，最终影响化学动力学。概念上，HB对化学物质的稳定性具有双重影响，第一是实际分子内HB力的稳定效果，第二是Hb浓度施加的环应变的稳定作用。通过确定具有Hb的化学物质或过渡状态的最小能量簇之间的差异和没有Hb（非氢键（NHB））来量化总体效果。评估Hb对物种和过渡迹歌曲术的稳定效应，还考虑了对计算速率常数的影响。我们的研究结果表明，对于大多数物种和过渡态，HB将其能量稳定多达2.5千卡/摩尔。然而，对于几种所考虑的物种，发现NHB塑套剂更稳定，最高可达2.7千卡/摩尔。为了研究Hb对速率常数的影响，基于最小能量塑壳的结构相似性分为两组（组1和二组）的反应

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