OH 自由基引发的二氯四氟丙烯 (CF3─CF=CCl2) 的对流层氧化：反应机理、动力学研究和大气影响,ACS Earth and Space Chemistry

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OH 自由基引发的二氯四氟丙烯 (CF3─CF=CCl2) 的对流层氧化：反应机理、动力学研究和大气影响
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2022-06-09 , DOI: 10.1021/acsearthspacechem.2c00072
Rabu Ranjan Changmai ₁ , Manabendra Sarma ₁

Affiliation

对大气中存在的氧化剂引发的卤代烯烃进行详细的降解研究至关重要，因为它能够释放游离卤素，从而在很大程度上影响环境。在这项工作中，我们研究了羟基自由基 (·OH) 引发的卤代烯烃 1,1-dichloro-2,3,3,3-tetrafluoroprop-1-ene, CF ₃ CF =CCl _{2的降解。}(CFP) 在大气中。我们提出反应通过两种方式进行：（i）双键任一侧的加成反应，和（ii）Cl-抽象反应。我们使用了密度泛函理论 (DFT) 和后 Hartree-Fock 方法以及三重相关一致基组、用于几何优化的 cc-pVTZ 和频率计算。使用上述理论精度研究热力学和动力学参数。势能面 (PES) 表明，这两种加成反应本质上都是放热反应，而 Cl 抽象反应是吸热反应。动力学和支化率计算结果表明，在双键碳原子（C1 和C2）上添加·OH 自由基比Cl-抽象反应更占优势。发现使用 M06-2X 函数在 298 K 计算的总速率常数与实验结果比后 Hartree-Fock，MP2 方法更接近。CFP 的大气寿命和臭氧消耗潜能值 (ODP) 计算为 2.48 天和 7.60 × 10^–5，分别。最后，CFP 的光化学臭氧生成潜力 (POCP) 估计为 6.40。

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Tropospheric Oxidation of Dichlorotetrafluoropropene (CF3─CF═CCl2) Initiated by OH Radical: Reaction Mechanisms, Kinetic Studies, and Atmospheric Implications

A detailed degradation study of the halogenated alkenes initiated by oxidants present in the atmosphere is of utmost importance because of its ability to release free halogen, which affects the environment to a large extent. In this work, we have studied the hydroxyl radical (·OH) initiated degradation of a halogenated alkene, 1,1-dichloro-2,3,3,3-tetrafluoroprop-1-ene, CF₃CF═CCl₂ (CFP) in the atmosphere. We have proposed that the reaction proceeds via two ways: (i) addition reactions to either side of the double bond, and (ii) Cl-abstraction reactions. We have used both the Density Functional Theory (DFT) and post-Hartree–Fock methods with triple-ζ correlation consistent basis sets, cc-pVTZ for geometry optimization, and frequency calculation. Thermodynamic and kinetic parameters are studied using the above-mentioned theoretical accuracies. The potential energy surface (PES) showed that both the addition reactions are exothermic in nature, whereas Cl-abstraction reactions are endothermic. The kinetic and branching ratio calculation results revealed that the addition of an ·OH radical to double bonded carbon atoms (C1 and C2) is more dominant than the Cl-abstraction reactions. The overall rate constant calculated at 298 K using the M06-2X functional is found to be in closer approximation with the experimental results than the post-Hartree–Fock, MP2 method. The atmospheric lifetime and ozone depletion potential (ODP) of CFP are calculated as 2.48 days and 7.60 × 10^–5, respectively. Finally, the photochemical ozone creation potential (POCP) of CFP is estimated to be 6.40.

更新日期：2022-06-09

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