Vijayakumar S, Wilmouth David M
Harvard John A. Paulson School of Engineering and Applied Sciences and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 United States.
J Phys Chem A. 2023 Aug 31;127(34):7284-7294. doi: 10.1021/acs.jpca.3c02200. Epub 2023 Aug 18.
Chlorinated very short-lived substances (VSLSs), which are not controlled by the Montreal Protocol, are of current concern with regard to recovery of stratospheric ozone. Further study is needed on the temperature dependences of chlorinated VSLSs relevant to atmospheric conditions. Here, the kinetics of chlorinated VSLSs, such as chloroform (CHCl), dichloromethane (CHCl), dichloroethane (CHClCHCl), and trichloroethene (CHCl) reacting with chlorine atoms, were investigated between 180 and 400 K, expanding the range of temperatures relative to previous studies. RRKM/Master Equation and Canonical Variational Transition State Theory were utilized to calculate the rate coefficients using the MultiWell suite of programs. CCSD(T), QCISD(T), and M062X with aug-cc-pV(T+d)Z levels of theory were used to calculate the kinetic parameters. Arrhenius equations obtained from fits to the calculated rate coefficients are = (2.66 ± 0.7) × 10 exp [(-927 ± 131)/] cm molecule s, = (8.99 ± 0.3) × 10 exp [(-957 ± 19)/] cm molecule s, = (1.51 ± 0.16) × 10 exp [(-714 ± 54)/] cm molecule s, and = (9.17 ± 1.8) × 10 exp [(612 ± 101)/] cm molecule s for the reactions of CHCl, CHCl, CHClCHCl, and CHCl with Cl atoms, respectively. The rate coefficients for the reactions of chlorinated VSLSs with Cl atoms from this study are compared with the most recent recommended values from the NASA/JPL and IUPAC evaluations and with literature values. The reactivity trends of the reactions are discussed.
不受《蒙特利尔议定书》管控的氯化极短寿命物质（VSLSs），目前在平流层臭氧恢复方面受到关注。需要对与大气条件相关的氯化VSLSs的温度依赖性进行进一步研究。在此，研究了氯仿（CHCl）、二氯甲烷（CHCl）、二氯乙烷（CHClCHCl）和三氯乙烯（CHCl）等氯化VSLSs与氯原子反应的动力学，反应温度范围为180至400 K，相较于之前的研究扩大了温度范围。利用RRKM/主方程和正则变分过渡态理论，通过MultiWell程序套件计算速率系数。使用CCSD(T)、QCISD(T)和理论水平为aug-cc-pV(T+d)Z的M062X来计算动力学参数。通过对计算得到的速率系数进行拟合得到的阿伦尼乌斯方程分别为：对于CHCl与Cl原子的反应，= (2.66 ± 0.7) × 10 exp [(-927 ± 131)/] cm molecule s；对于CHCl与Cl原子的反应，= (8.99 ± 0.3) × 10 exp [(-957 ± 19)/] cm molecule s；对于CHClCHCl与Cl原子的反应，= (1.51 ± 0.16) × 10 exp [(-714 ± 54)/] cm molecule s；对于CHCl与Cl原子的反应，= (9.17 ± 1.8) × 10 exp [(612 ± 101)/] cm molecule s。将本研究中氯化VSLSs与Cl原子反应的速率系数与美国国家航空航天局/喷气推进实验室（NASA/JPL）和国际纯粹与应用化学联合会（IUPAC）评估的最新推荐值以及文献值进行了比较。讨论了这些反应的反应活性趋势。
