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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Effect of Halogenation on the Mechanism of the Atmospheric Reactions between Methylperoxy Radicals and NO. A computational Study
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Effect of Halogenation on the Mechanism of the Atmospheric Reactions between Methylperoxy Radicals and NO. A computational Study

机译：卤化对甲基过氧自由基与NO之间大气反应机理的影响。计算研究

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摘要

The mechanism of the reactions between the halogenated methylperoxy radicals, CHX2O2 (X ) F, Cl), and NO is investigated by using ab initio and density functional quantum mechanical methods. Comparison is made with the mechanism of the CH3O2 + NO reaction. The most important energy minima in the potential energy surface are found to be the two conformers of the halogenated methyl peroxynitrite association adducts, CHX2OONOcp and CHX2OONOtp, and the halogenated methyl nitrates, CHX2ONO2. The latter are suggested to be formed through the one-step isomerization of the peroxynitrite adduct and may lead upon decomposition to carbonylated species, CX2O + HONO and CHXO + XNO2. The ambiguous issue of the unimolecular peroxynitrite to nitrate isomerization is reconsidered, and the possibility of a triplet transition state involvement in the ROONOtp T RONO2 rearrangement is examined. The overall calculations and the detailed correlation with the methyl system show the significant effect of the halogenation on the lowering of the entrance potential energy well which corresponds to the formation of the peroxynitrites. The increased attractive character of the potential energy surface found upon halogenation combined with the increased exothermicity of the CHX2O2 + NO f CHX2O + NO2 reaction are suggested to be the important factors contributing to the enhanced reactivity of the halogenated reactions relative to CH3O2 + NO. The calculated heat of formation values indicate the large stabilization of the fluorinated derivatives.
机译：使用从头算和密度泛函量子力学方法研究了卤代甲基过氧自由基，CHX2O2（X）F，Cl）和NO之间的反应机理。比较了CH3O2 + NO反应的机理。发现在势能表面上最重要的最小能量是卤化甲基过氧亚硝酸盐缔合加合物CHX2OONOcp和CHX2OONOtp以及卤化硝酸甲酯CHX2ONO2的两个构象。建议后者通过过氧亚硝酸盐加合物的一步异构化形成，并可能在分解时生成羰基化物质CX2O + HONO和CHXO + XNO2。重新考虑了单分子过氧亚硝酸盐对硝酸盐异构化的含糊不清的问题，并研究了三重态过渡态参与ROONOtp T RONO2重排的可能性。总体计算和与甲基系统的详细相关性表明，卤化对降低入口势能阱具有显着影响，这对应于过氧亚硝酸盐的形成。卤化后发现的势能表面的吸引力增加，加上CHX2O2 + NO f CHX2O + NO2反应的放热增加，被认为是有助于卤化反应相对于CH3O2 + NO增强反应性的重要因素。计算出的地层热值表明氟化衍生物具有很大的稳定性。

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