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1.
Phys Chem Chem Phys ; 25(14): 10185, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36950873

RESUMO

Correction for 'Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms of the reactions with Cl atoms, OH radicals, and O3' by Mads P. Sulbaek Andersen et al., Phys. Chem. Chem. Phys., 2022, 24, 7356-7373, https://doi.org/10.1039/D1CP04877E.

2.
Phys Chem Chem Phys ; 24(12): 7356-7373, 2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35266471

RESUMO

Smog chambers interfaced with in situ FT-IR detection were used to investigate the kinetics and mechanisms of the Cl atom, OH radical, and O3 initiated oxidation of (Z)- and (E)-1,2-dichloroethene (CHClCHCl) under atmospheric conditions. Relative and absolute rate methods were used to measure k(Cl + (Z)-CHClCHCl) = (8.80 ± 1.75) × 10-11, k(Cl + (E)-CHClCHCl) = (8.51 ± 1.69) × 10-11, k(OH + (Z)-CHClCHCl) = (2.02 ± 0.43) × 10-12, k(OH + (E)-CHClCHCl) = (1.94 ± 0.43) × 10-12, k(O3 + (Z)-CHClCHCl) = (4.50 ± 0.45) × 10-21, and k(O3 + (E)-CHClCHCl) = (1.02 ± 0.10) × 10-19 cm3 molecule-1 s-1 in 700 Torr of N2/air diluent at 298 ± 2 K. Pressure dependencies for the Cl atom reaction kinetics were observed for both isomers, consistent with isomerization occurring via Cl atom elimination from the chemically activated CHCl-CHCl-Cl adduct. The observed products from Cl initiated oxidation were HC(O)Cl (117-133%), CHCl2CHO (29-30%), and the corresponding CHClCHCl isomer (11-20%). OH radical initiated oxidation gives HC(O)Cl as a major product. For reaction of OH with (E)-CHClCHCl, (Z)-CHClCHCl was also observed as a product. A significant chlorine atom elimination channel was observed experimentally (HCl yield) and supported by computational results. Photochemical ozone creation potentials of 12 and 11 were estimated for (Z)- and (E)-CHClCHCl, respectively. Finally, an empirical kinetic relationship is explored for the addition of OH radicals or Cl atoms to small alkenes. The results are discussed in the context of the atmospheric chemistry of (Z)- and (E)-CHClCHCl.

3.
Phys Chem Chem Phys ; 20(45): 28796-28809, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30418435

RESUMO

Photochemical reactors were used to study the kinetics and mechanisms of reactions of Cl atoms and OH radicals with hexa- and penta-fluorobenzene (C6F6, C6F5H) in 700 Torr total pressure of N2, air, or O2 diluent at 296 ± 2 K. C6F6 and C6F5H undergo ring-opening following 254 nm UV irradiation, but with small quantum yields (φ < 0.03). Reaction of Cl atoms with C6F6 proceeds via adduct formation, while the reaction of Cl atoms with C6F5H proceeds via hydrogen abstraction and adduct formation. C6F6-Cl and C6F5H-Cl adducts decompose rapidly (k ∼ 105-106 s-1) reforming the reactants, and react with Cl atoms to form products. The fraction of adduct reacting with Cl atoms increases with steady state Cl atom concentration, resulting in an increasing apparent effective Cl atom rate constant. The rate constant for the H-abstraction channel for Cl + C6F5H is estimated at (7.3 ± 5.7) × 10-16 cm3 molecule-1 s-1. Establishment of the equilibrium between the adducts and the aromatic reactant + Cl occurs rapidly with equilibrium constants of K([adduct]/[aromatic][Cl]) = (1.96 ± 0.11) × 10-16 and (9.28 ± 0.11) × 10-17 cm3 molecule-1 for C6F6 and C6F5H, respectively. Reaction of the adducts with O2 occurs slowly with estimated rate constants of <7 and <4 × 10-18 cm3 molecule-1 s-1 for C6F6-Cl and C6F5H-Cl, respectively. The rate constants for reaction of OH radicals with C6F6 and C6F5H were determined to be (2.27 ± 0.49) × 10-13 and (2.56 ± 0.62) × 10-13 cm3 molecule-1 s-1, respectively. UV and IR spectra of C6F6 and C6F5H at 296 ± 1 K were collected and calibrated. Results are discussed in the context of available literature data for reactions of Cl atoms and OH radicals with halogenated aromatic compounds.

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