The atmospheric oxidation mechanism and kinetics of 3, 3, 4, 4, 5, 5- hexafluorocyclopentene (HFC-C1436) initiated by OH radical has been investigated by using electronic structure calculations. Canonical variation transition state theory was employed to predict the rate constant for the favourable OH-addition reaction pathway. Under atmospheric condition, the initially formed HFC-C1436-OH adduct, reacts rapidly with O2 and NO• to form the peroxy and alkoxy radical, which subsequently react with HO2 and O2 to form 2,2,3,3,4,4-Hexafluoro-5-hydroperoxy-cyclopentanol (P1), 3,3,4,4,5,5-Hexafluoro-cyclopentane-1,2-diol (P2) and 2,2,3,3,4,4-Hexafluoro-5-hydroxy-cyclopentane (P3). Two different ring opening reaction pathways of alkoxy radical were studied. In addition to the products, P1, P2 and P3, the possible end products identified from ring opening reactions are CO, CO2, COF2 and glyoxal which will induce less environmental impacts than the chloroflurocarbons (CFC). The rate constant calculated for the favourable initial reaction at 298 K is 0.842 × 10−13 cm3molecule−1s−1 and is in agreement with the available experimental value. The atmospheric lifetime, global warming potentials (GWPs) for different time horizon and photochemical ozone creation potential (POCP) were also calculated.

中文翻译：

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OH自由基引发HFC-C1436大气氧化的第一性原理研究

通过电子结构计算研究了由OH自由基引发的3,3,4,4,4,5,5-六氟环戊烯（HFC-C1436）的大气氧化机理和动力学。采用典型的变化过渡态理论来预测有利的OH加成反应途径的速率常数。在大气条件下，最初形成的HFC-C1436-OH加合物与O2和NO•迅速反应形成过氧和烷氧基，然后与HO2和O2反应形成2,2,3,3,4,4-六氟-5-氢过氧环戊醇（P1），3,3,4,4,5,5-六氟环戊烷1,2-二醇（P2）和2,2,3,3,4,4-六氟- 5-羟基环戊烷（P3）。研究了烷氧基自由基的两种不同的开环反应途径。除了产品P1，P2和P3，从开环反应中识别出的最终产品可能是CO，CO2，COF2和乙二醛，与氯氟烃（CFC）相比，它们对环境的影响较小。在298 K时为有利的初始反应计算出的速率常数为0.842×10-13 cm3分子-1s-1，与可用的实验值一致。还计算了大气寿命，不同时间段的全球变暖潜能值（GWP）和光化学臭氧产生潜能值（POCP）。