Atmospheric oxidation chemistry of hexafluoroisobutylene initiated by OH radical: Kinetics and mechanism

“…The reason for NO addition followed by an O 2 molecule is that the concentration of O 2 in the atmosphere is higher than that of NO. 81 The role of nitrogen oxides (NO x # NO + NO 2 ) and ozone (O 3 ) in atmospheric photochemistry is extensively understood. 82 NO and NO 2 , which impair surface air quality and regulate the Fig.…”

Section: Rsimentioning

confidence: 99%

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF₂CFCl) initiated by OH radicals

Balsini

Shiroudi

Hatamjafari

et al. 2023

Phys. Chem. Chem. Phys.

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“…This reaction sequence occurs because the concentration of O 2 is higher than that of NO in the atmosphere. [47] NO is a critical component in the primary mechanism of O 3 formation in the troposphere. NO reacts with peroxy species, converting NO to NO 2 , which is then photolyzed to form O 3 and regenerate NO.…”

Section: Secondary Reactionsmentioning

confidence: 99%

Chemical Investigation on the Mechanism and Kinetics of the Atmospheric Degradation Reaction of Trichlorofluoroethene by OH⋅ and Its Subsequent Fate in the Presence of O₂/NOx

Shiroudi,

Czub,

Altarawneh

2023

ChemPhysChem

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The M06‐2X/6‐311++G(d,p) level of theory was used to examine the degradation of Trichlorofluoroethene (TCFE) initiated by OH⋅ radicals. Additionally, the coupled‐cluster single‐double with triple perturbative [CCSD(T)] method was employed to refine the single‐point energies using the complete basis set extrapolation approach. The results indicated that OH‐addition is the dominant pathway. OH⋅ adds to both the C1 and C2 carbons, resulting in the formation of the C(OH)Cl2−⋅CClF and ⋅CCl2−C(OH)ClF species. The associated barrier heights were determined to be 1.11 and −0.99 kcal mol−1, respectively. Furthermore, the energetic and thermodynamic parameters show that pathway 1 exhibits greater exothermicity and exergonicity compared to pathway 2, with differences of 8.11 and 8.21 kcal mol−1, correspondingly. The primary pathway involves OH addition to the C2 position, with a rate constant of 6.2×10−13 cm3 molecule−1 sec−1 at 298 K. This analysis served to estimate the atmospheric lifetime, along with the photochemical ozone creation potential (POCP) and ozone depletion potential (ODP). It yielded an atmospheric lifetime of 8.49 days, an ODP of 4.8×10−4, and a POCP value of 2.99, respectively. Radiative forcing efficiencies were also estimated at the M06‐2X/6‐311++G(d,p) level. Global warming potentials (GWPs) were calculated for 20, 100, and 500 years, resulting in values of 9.61, 2.61, and 0.74, respectively. TCFE is not expected to make a significant contribution to the radiative forcing of climate change. The results obtained from the time‐dependent density functional theory (TDDFT) indicated that TCFE and its energized adducts are unable to photolysis under sunlight in the UV and visible spectrum. Secondary reactions involve the [TCFE‐OH−O2]⋅ peroxy radical, leading subsequently to the [TCFE−OH−O]⋅ alkoxy radical. It was found that the alkoxy radical resulting from the peroxy radical can lead to the formation of phosgene (COCl2) and carbonyl chloride fluoride (CClFO), with phosgene being the primary product.

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Atmospheric oxidation chemistry of hexafluoroisobutylene initiated by OH radical: Kinetics and mechanism

Cited by 2 publications

References 59 publications

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF₂CFCl) initiated by OH radicals

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF₂CFCl) initiated by OH radicals

Chemical Investigation on the Mechanism and Kinetics of the Atmospheric Degradation Reaction of Trichlorofluoroethene by OH⋅ and Its Subsequent Fate in the Presence of O₂/NOx

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Atmospheric oxidation chemistry of hexafluoroisobutylene initiated by OH radical: Kinetics and mechanism

Cited by 2 publications

References 59 publications

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF2CFCl) initiated by OH radicals

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF2CFCl) initiated by OH radicals

Chemical Investigation on the Mechanism and Kinetics of the Atmospheric Degradation Reaction of Trichlorofluoroethene by OH⋅ and Its Subsequent Fate in the Presence of O2/NOx

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Product

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About

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF₂CFCl) initiated by OH radicals

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF₂CFCl) initiated by OH radicals

Chemical Investigation on the Mechanism and Kinetics of the Atmospheric Degradation Reaction of Trichlorofluoroethene by OH⋅ and Its Subsequent Fate in the Presence of O₂/NOx