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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Hydroxyalkoxy Radicals: Importance of Intramolecular Hydrogen Bonding on Chain Branching Reactions in the Combustion and Atmospheric Decomposition of Hydrocarbons
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Hydroxyalkoxy Radicals: Importance of Intramolecular Hydrogen Bonding on Chain Branching Reactions in the Combustion and Atmospheric Decomposition of Hydrocarbons

机译：羟烷氧基自由基：分子内氢键对碳氢化合物燃烧和大气分解中链支化反应的重要性

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摘要

During both the atmospheric oxidation and combustion of volatile organic compounds, sequential addition of oxygen can lead to compounds that contain multiple hydrogen-bonding sites. The presence of two or more of these sites on a hydrocarbon introduces the possibility of intramolecular H-bonding, which can have a stabilizing effect on the reactants, products, and transition states of subsequent reactions. The present work compares the absolute energies of two sets of conformations, those that contain intramolecular H-bonds and those that lack intramolecular H-bonds, for each reactant, product, and transition state species in the 1,2 through 1,7 H-migrations and C alpha C beta, C alpha H, and C alpha OH-bond scission reactions in the n-hydroxyeth-1-oxy through n-hydroxyhex-1-oxy radicals, for n ranging from 1 to 6. The difference in energy between the two conformations represents the balance between the stabilizing effects of H-bonds and the steric cost of bringing the two H-bonding sites together. The effect of intramolecular H-bonding and the OH group is assessed by comparing the net intramolecular H-bond stabilization energies, the reaction enthalpies, and barrier heights of the n-hydroxyalkoxy radical reactions with the corresponding alkoxy radicals values. The results suggest that there is a complex dependence on the location of the two H-bonding groups, the location of the abstraction or bond scission, and the shape of the transition state that dictates the extent to which intramolecular H-bonding effects the relative importance of H-migration and bond scission reactions for each n-hydroxyalkoxy radical. These findings have important implications for future studies on hydrocarbons with multiple H-bonding sites.
机译：在大气氧化和挥发性有机化合物燃烧期间，氧气的顺序添加会导致包含多个氢键结合位点的化合物。烃上两个或多个这些位点的存在引入了分子内氢键的可能性，这可能对反应物，产物和后续反应的过渡态具有稳定作用。本工作比较了1,2至1,7 H-中的每种反应物，产物和过渡态物种的两种构象的绝对能量，其中包括分子内氢键的构象和缺少分子内氢键的构象。 n羟基乙基-1-氧基中通过n-羟基己-1-氧基进行的迁移和C alpha C beta，C alpha H和C alpha OH键断裂反应，n范围为1至6。在两个构象之间的平衡表示在H键的稳定作用和将两个H键结合在一起的空间成本之间的平衡。通过将分子内氢键的净稳定能，反应焓和正羟基烷氧基自由基反应的势垒高度与相应的烷氧基自由基值进行比较，可以评估分子内H键和OH基团的作用。结果表明，对两个H键基团的位置，抽象或键断裂的位置以及过渡状态的形状有着复杂的依赖性，该状态决定了分子内H键影响相对重要性的程度每个正羟基烷氧基的氢迁移和键断裂反应的关系这些发现对未来对具有多个氢键位的烃的研究具有重要意义。

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