A quantum chemical study on •Cl-initiated atmospheric degradation of CH3CFClO2

Publication date: Available online 3 February 2020Source: Journal of Molecular StructureAuthor(s): Yunju Zhang, Bing He, Yuxi SunAbstractQuantum chemical method (BMC-CCSD//B3LYP/6–311++G (d,p)) was employed to research the mechanism and kinetics of the gas-phase of the CH3CFClO2 + Cl reaction. The results show that, on the singlet PES, the reaction take place through the chlorine addition to the terminal-O atom of CH3CFClO2 producing adduct IM1 (CH3CFClOOCl), and then further dissociate or rearrangement into many produces. On the triplet PES, the most feasible channel is production of P7T (CH2CFClO2 + HCl) by direct H-abstraction. The rate constants for the production of IM1 (CH3CFClOOCl), P1 (CH3CFO + ClClO), P2 (CH3CFO + ClOCl) and P7T (CH2CFClO2 + HCl) are calculated by using RRKM-TST theory, indicating that the production of IM1 (CH3CFClOOCl) (kIM1) with the binding energy of 33.84 kcal/mol is the dominant product pathway at T ≤ 800 K; meanwhile, P1 (CH3CFO + ClClO) and P7T (CH2CFClO2 + HCl) are the dominant products at 800 < T ≤ 1000 K and T > 1000 K, respectively, as well as the rate constants of P1 (CH3CFO + ClClO) and P7T (CH2CFClO2 + HCl) show positive temperature dependence at 200–3000 K. At 298, 500, 1000 and 3000 K, the total rate constants exhibited typical falloff behavior. The estimated atmospheric lifetime of CH3CFClO2 in Cl is around 3.0 days. TD-DFT computations imply that IM1 (CFCl2CH2OOCl) and IM2 (CFCl2CH2OC...
Source: Journal of Molecular Structure - Category: Molecular Biology Source Type: research