FTIR study of the Cl- and Br-atom initiated oxidation of trichloroethylene

Catoire, Valéry; Ariya, Parisa A.; Niki, H.; Harris, G. W.

doi:10.1002/(sici)1097-4601(1997)29:9<695::aid-kin7>3.0.co;2-p

Cited by 16 publications

(28 citation statements)

References 27 publications

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“…Another potential complication arises from the fact that, in studies involving k 1 , Cl atoms are generated [32]:…”

Section: Rate Coefficient Data For K 1 -Kmentioning

confidence: 99%

“…However, despite the importance of these reactions in the analysis of surface ozone-depletion chemistry, no data at temperatures below 293 K have been reported. In addition, an investigation of the temperature-and NO xdependence of the mechanism of the Br-atom -initiated oxidation of acetylene, trichloroethene, and tetrachloroethene has been made for comparison with previous room-temperature, NO x -free studies [28,31,32,34,45]. Data are obtained over the temperature range 228 -298 K in Ϸ1 atm air.…”

Section: Introductionmentioning

confidence: 99%

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Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Ramacher

Tyndall

2001

Int. J. Chem. Kinet.

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“…Another potential complication arises from the fact that, in studies involving k 1 , Cl atoms are generated [32]:…”

Section: Rate Coefficient Data For K 1 -Kmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Ramacher

Tyndall

2001

Int. J. Chem. Kinet.

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“…It is to be noted that secondary reactions of Cl-atoms with CCl 3 CHO and CCI 3 C(O)CI are slow compared to the Cl-atom reaction of trichloroethene should thus be negligible in the range of conversion of trichloroethene used here. We observed CHCIO in this system, but as explained in detail by Catoire et al (1996) who studied the product distributions of channels (la) and (1 b) individually, the amount of formyl chloride from the reaction (lb) ought to be negligible. Therefore, reaction (la) followed by reactions (3a) and (3b) account for the total degradation of trichloroethene.…”

Section: Mechanistic Studies Ofcl-atom +Chlorinated Ethenesmentioning

confidence: 63%

“…The full description of these kinetic studies is explained elsewhere (Ariya, 1996;Catoire et al, 1996). In brief, ethane was used as the reference molecule in Cl reactions while ethene served as reference in the Br+C 2 HCI 3 and propane in the Br + C 2 Cl 4 systems.…”

Section: Kineticsmentioning

confidence: 99%

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Trichloroethene and tetrachloroethene: tropospheric probes for Cl- and Br-atom reactions during the polar sunrise

Ariya

Catoire

Sander

et al. 1997

Tellus B: Chemical and Physical Meteorology

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We report the results of laboratory and modeling investigations of the atmospheric fate of chlorinated ethenes and their role as indicators of halogen reactions in the springtime Arctic troposphere. The kinetics and mechanism of the gas-phase reactions of Cl-and Br-atoms with tetrachloroethene were studied using a Fourier transform infrared spectrometer (FTIR) in 93.3 kPa air and T=296±2 K. Along with our previous study on Cl and Br atom reactions of trichloroethene, using the known rate of the Cl +ethane reaction as reference, the values of 7.2±O.2 x lO-l1 and 3.8±O.2 x lO-l1 cm 3 molecule-1 S-1 were obtained for the Cl-atom reaction rate constants of tri-and tetrachloroethene, respectively. For the Br-atom reactions, using ethene and propane as the reference molecules, we report the absolute values of 1.1 ±O.1 x lO-13 and 9.0±O.1 x lO-17 cm 3 molecule-1 S-1 for the rates of Br attack on tri-and tetrachloroethene. The major products were XCI 2 C-C{O)CI (X=H in trichloroethene and X=CI in tetrachloroethene) and XBrClC-C{O)Cl in Cl-atom and Br-atom initiated reactions, respectively. We also observed phosgene and formyl cWoride in the reactions of trichloroethene and phosgene in the tetrachloroethene reactions and report the branching ratios for these channels. Our observations show that the addition of Cl-atoms to the less substituted carbon is the major reaction pathway and that a Cl-atom is subsequently released after either CI-or Br-atoms add to trichloroethene or tetrachloroethene, leading to the recycling of active halogen. We carried out a box modeling exercise to apply the kinetic and mechanistic information obtained in this work to the interpretation of measurements of C 2 HCI 3 , C 2 Cl 4 and other hydrocarbons in the Arctic troposphere. Our results demonstrate that the presence of both CI-and Br-atoms is required to explain the decreases in the concentrations of these species during ozone depletion events in the Arctic, that the amount of Cl-and Br-atoms required to account for the observed decreases of chlorinated ethenes is also sufficient to completely destroy ozone. However, at the low concentrations of chlorinated species observed, the cycling of Br to Cl through the studied reactions is not a significant effect in the atmosphere.

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A global model of tropospheric chlorine chemistry: Organic versus inorganic sources and impact on methane oxidation

et al. 2016

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Chlorine atoms (Cl) are highly reactive toward hydrocarbons in the Earth's troposphere, including the greenhouse gas methane (CH4). However, the regional and global CH4 sink from Cl is poorly quantified as tropospheric Cl concentrations ([Cl]) are uncertain by ~2 orders of magnitude. Here we describe the addition of a detailed tropospheric chlorine scheme to the TOMCAT chemical transport model. The model includes several sources of tropospheric inorganic chlorine (Cly), including (i) the oxidation of chlorocarbons of natural (CH3Cl, CHBr2Cl, CH2BrCl, and CHBrCl2) and anthropogenic (CH2Cl2, CHCl3, C2Cl4, C2HCl3, and CH2ClCH2Cl) origin and (ii) sea‐salt aerosol dechlorination. Simulations were performed to quantify tropospheric [Cl], with a focus on the marine boundary layer, and quantify the global significance of Cl atom CH4 oxidation. In agreement with observations, simulated surface levels of hydrogen chloride (HCl), the most abundant Cly reservoir, reach several parts per billion (ppb) over polluted coastal/continental regions, with sub‐ppb levels typical in more remote regions. Modeled annual mean surface [Cl] exhibits large spatial variability with the largest levels, typically in the range of 1–5 × 104 atoms cm−3, in the polluted northern hemisphere. Chlorocarbon oxidation provides a tropospheric Cly source of up to ~4320 Gg Cl/yr, sustaining a background surface [Cl] of <0.1 to 0.5 × 103 atoms cm−3 over large areas. Globally, we estimate a tropospheric methane sink of ~12–13 Tg CH4/yr due the CH4 + Cl reaction (~2.5% of total CH4 oxidation). Larger regional effects are predicted, with Cl accounting for ~10 to >20% of total boundary layer CH4 oxidation in some locations.

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FTIR study of the Cl- and Br-atom initiated oxidation of trichloroethylene

Abstract: The Cl-and Br-initiated oxidations of CHCl"CCl 2 in 700 torr of air at 296 K have been studied using a Fourier transform infrared spectrometer. Rate constants k(Cl ϩ and *Present address:

Cited by 16 publications

References 27 publications

Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Trichloroethene and tetrachloroethene: tropospheric probes for Cl- and Br-atom reactions during the polar sunrise

A global model of tropospheric chlorine chemistry: Organic versus inorganic sources and impact on methane oxidation

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