Relative Rate and Product Studies of the Reactions of Atomic Chlorine with Tetrafluoroethylene, 1,2-Dichloro-1,2-difluoroethylene, 1,1-Dichloro-2,2-difluoroethylene, and Hexafluoro-1,3-butadiene in the Presence of Oxygen

Herath, Thushani N.; Clinch, Eric C.; Orozco, Ivan; Raign, Erin L.; Marshall, Paul

doi:10.1021/acs.jpca.6b05305

Cited by 5 publications

(5 citation statements)

References 34 publications

(63 reference statements)

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“… τ = 1 k 0.25em false( overall false) × false[ OH false] where k (overall) is the overall rate coefficient of the reaction studied with OH radicals, and [OH] is the global average concentration of OH radicals. The concentration of OH radicals is considered to be 1.0 × 10 6 molecules cm –3 . , …”

Section: Resultsmentioning

confidence: 99%

“…The concentration of OH radicals is considered to be 1.0 × 10 6 molecules cm −3 . 57,58 The atmospheric lifetimes (τ) of A, B, and C at 298.15 K are 36.75, 35.11, and 17.45 days, respectively. This indicates that A and B have more chance than C to interact directly with human beings and the environment when emitted in the atmosphere as it will remain in the atmosphere for a longer period.…”

Section: Atmospheric Implications 341 Atmospheric Lifetimes (τ)mentioning

confidence: 99%

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Investigating the Atmospheric Fate and Kinetics of OH Radical-Initiated Oxidation Reactions for Epoxybutane Isomers: Theoretical Insight

Daimari,

Changmai,

Sarma

2024

J. Phys. Chem. A

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Epoxides, which belong to the category of oxygenated volatile organic compounds (OVOCs), are emitted into the atmosphere by an array of sources and can impact both human and environmental well-being significantly. This study involves comprehensive computational analyses aimed at investigating the mechanism, thermodynamic aspects, and reaction kinetics associated with hydrogen abstraction reactions of cis-2,3-epoxybutane, trans-2,3epoxybutane, and 1,2-epoxybutane by OH radicals. The potential energy diagrams involving all of the species for each specific pathway were constructed at the CCSD(T)/aug-cc-pVTZ//M06-2X/cc-pVTZ level of theory. The rate coefficients for all possible pathways were calculated using the Rice−Ramsperger−Kassel−Marcus master equation (RRKM-ME) corrected by Eckart tunneling within the 200−350 K temperature range and 1 atm pressure. The overall rate coefficients of the reaction of cis-2,3-epoxybutane, trans-2,3epoxybutane, and 1,2-epoxybutane with OH radicals at 298.15 K were found to be 0.32 × 10 −12 , 0.33 × 10 −12 , and 0.66 × 10 −12 cm 3 molecule −1 s −1 , respectively. We also studied the atmospheric lifetime and photochemical ozone creation potential (POCP) of all three compounds. In addition, we have provided extensive degradation pathways for the product radicals formed from the initial reaction with OH radicals in the presence of O 2 and NO. The study showed that the product radicals can result in various harmful end products, including grade 1 and grade 2 carcinogens, as listed by the World Health Organization (WHO).

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Section: Resultsmentioning

confidence: 99%

Section: Atmospheric Implications 341 Atmospheric Lifetimes (τ)mentioning

confidence: 99%

Investigating the Atmospheric Fate and Kinetics of OH Radical-Initiated Oxidation Reactions for Epoxybutane Isomers: Theoretical Insight

Daimari,

Changmai,

Sarma

2024

J. Phys. Chem. A

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“…We use IR spectroscopy to probe the chemistry initiated by photolytically generated chlorine atoms, evaluate reaction kinetics, identify products and quantify product yields. Our apparatus has been described in detail elsewhere [12]. In overview, mixtures of HFB and molecular chlorine diluted in a large excess of argon bath gas at 1 bar pressure and room temperature were exposed to steady UV illumination at 365 nm from a mercury lamp over time scales of 10-50 min.…”

Section: Experimental Methodsmentioning

confidence: 99%

Gas-Phase Chemistry of 1,1,2,3,3,4,4-Heptafluorobut-1-ene Initiated by Chlorine Atoms

Sapkota

Marshall

2022

Molecules

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The possibility of mitigating climate change by switching to materials with low global warming potentials motivates a study of the spectroscopic and kinetic properties of a fluorinated olefin. The relative rate method was used to determine the rate constant for the reaction of heptafluorobut-1-ene (CF2=CFCF2CF2H) with chlorine atoms in air. A mercury UV lamp was used to generate atomic chlorine, which initiated chemistry monitored by FTIR spectroscopy. Ethane was used as the reference compound for kinetic studies. Oxidation of heptafluorobut-1-ene initiated by a chlorine atom creates carbonyl difluoride (CF2=O) and 2,2,3,3 tetrafluoropropanoyl fluoride (O=CFCF2CF2H) as the major products. Anharmonic frequency calculations allowing for several low-energy conformations of 1,1,2,3,3,4,4 heptafluorobut-1-ene and 2,2,3,3 tetrafluoropropanoyl fluoride, based on density functional theory, are in good accord with measurements. The global warming potentials of these two molecules were calculated from the measured IR spectra and estimated atmospheric lifetimes and found to be small, less than 1.

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“…Commercial samples were purified by repeated freeze–pump–thaw cycles with liquid nitrogen. The general principles of relative rate measurements are well established , and we have described our apparatus and procedures in detail elsewhere . Briefly, molecular chlorine is photolyzed by steady UV illumination from a mercury pen lamp in the presence of the reactant ketone and a reference compound in a 100‐cm 3 Pyrex multipass IR cell, with a path length of 2.4 m. The Pyrex walls are expected to block lamp emission at 184 and 254 nm but not at 365 nm.…”

Section: Methodsmentioning

confidence: 99%

Relative Rate Studies of the Reactions of Atomic Chlorine with Acetone and Cyclic Ketones

Herath

Orozco

Clinch

et al. 2017

Int J of Chemical Kinetics

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Rate coefficients have been measured for Cl atom reactions under ambient conditions with acetone and four cyclic ketones. Cl was generated by UV photolysis of Cl 2 , and other species were monitored by FT-IR spectroscopy. The measurements yield k(Cl + acetone) = (2.0 ± 0.7) × 10 −12 , k(Cl + cyclobutanone) = (10.1 ± 0.8) × 10 −11 , k(Cl + cycloheptanone) = (24.0 ± 2.3) × 10 −11 , k(Cl + 2-methyl cyclopentanone) = (15.2 ± 1.2) × 10 −11 , and k(Cl + 2-methyl cyclohexanone) = (11.2 ± 1.0) × 10 −11 cm 3 molecule −1 s −1 , where the uncertainties represent 95% confidence limits. These results are discussed in the context of structure-activity relationships. We also present a prediction for Cl + cyclopropanone based on ab initio properties of the transition state.

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Relative Rate and Product Studies of the Reactions of Atomic Chlorine with Tetrafluoroethylene, 1,2-Dichloro-1,2-difluoroethylene, 1,1-Dichloro-2,2-difluoroethylene, and Hexafluoro-1,3-butadiene in the Presence of Oxygen

Cited by 5 publications

References 34 publications

Investigating the Atmospheric Fate and Kinetics of OH Radical-Initiated Oxidation Reactions for Epoxybutane Isomers: Theoretical Insight

Investigating the Atmospheric Fate and Kinetics of OH Radical-Initiated Oxidation Reactions for Epoxybutane Isomers: Theoretical Insight

Gas-Phase Chemistry of 1,1,2,3,3,4,4-Heptafluorobut-1-ene Initiated by Chlorine Atoms

Relative Rate Studies of the Reactions of Atomic Chlorine with Acetone and Cyclic Ketones

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