Photolysis study of fluorinated ketones under natural sunlight conditions

Díaz-de-Mera, Yolanda; Aranda, Alfonso; Notario, Alberto; Rodrı́guez, Ana; Rodrı́guez, Diana; Bravo, Iván

doi:10.1039/c5cp03527a

Cited by 9 publications

(15 citation statements)

References 24 publications

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“…4) and found to be in the range of (0.7-1.2)×10 -4 s -1 . Therefore, the observed photolysis rate corresponds to an effective quantum yield of ∅eff =0.015-0.035, which is in agreement with the values reported by D'Anna, et al and Díaz-de-Mera, et al 13 , 0.043±0.011…”

Section: Photolysis Of Perfluoro-supporting

confidence: 92%

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Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Ren

Bernard

Daële

et al. 2019

Environ. Sci. Technol.

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Perfluoroketones, used as replacement to halons and CFCs, are excluded from the Montreal Protocol because they are considered as non-ozone depleting substances. However, their chemical structure makes them possible greenhouse gases if their atmospheric lifetimes are long enough. To assess that possibility, we investigated the photolysis of perfluoro-2-methyl-3-pentanone (PF-2M3P), and perfluoro-3-methyl-2butanone (PF-3M2B) using outdoor atmospheric simulation chambers. In addition, the photolysis of a non fluorinated pentanone (2-methyl-3-pentanone, 2M3P) was studied. The results showed that photolysis is the dominant loss pathway of PF-2M3P and PF-3M2B in the troposphere whereas 2M3P is lost by both photolysis and gas phase reaction with atmospheric oxidants. The photolysis effective quantum yields of PF-2M3P, PF-3M2B and 2M3P were estimated and some of the main products identified. The photolysis of PF-2M3P and PF-3M2B was found to have a minor impact on the atmospheric burden of fluorinated acids. The atmospheric lifetimes of PF-2M3P, PF-3M2B and 2M3P were estimated to 3-11 days, 13 days and 1-2 days, respectively. Combining the obtained data, it has been concluded that with 100-year time horizon global warming potentials (GWP100) equivalent to <0.21, ~0.29 and ≤1.3×10-7 for PF-2M3P, PF-3M2B and 2M3P, respectively, these compounds will have a negligible impact on global warming.

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Section: Photolysis Of Perfluoro-supporting

confidence: 92%

“…between 220 and 400 nm at (300 ± 2) K are depicted in Figure 1 and absorption cross sections are provided in Table S1. obtained in the present work is higher than that reported by Díaz-de-Mera, et al 13 by 18% (max). To the best of our knowledge, the experimental UV spectrum of PF-3M2B…”

Section: Uv Absorption Cross Sectioncontrasting

confidence: 78%

Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Ren

Bernard

Daële

et al. 2019

Environ. Sci. Technol.

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“…The rate of reactions (23) and (24) were measured relative to reactions (25) and (26) Fig. 3 shows the loss of Z-and E-CF 3 CHQCHCF 3 versus the loss of the two reference compounds C 2 H 6 and n-C 4 H 10 in the presence of OD radicals.…”

Section: Relative Rate Study Of Zand E-cf 3 Chq Q Qchcf 3 + CLmentioning

confidence: 99%

“…UVB lights are expected to photolyze CF 3 CHClC(O)CF 3 , as has been observed for similar fluorinated ketones. 23,24 The products observed in the experiments using UVB lamps are therefore a combination of the reaction with Cl atoms and of the photolysis. The experiment using UVA lamps gives products of the reaction with Cl atoms only.…”

Section: Product Study Of Cf 3 Chclc(o)cf 3 + CLmentioning

confidence: 99%

Atmospheric chemistry of Z- and E-CF₃CHCHCF₃

Østerstrøm

Andersen

Sølling

et al. 2017

Phys. Chem. Chem. Phys.

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The atmospheric fates of Z- and E-CFCH[double bond, length as m-dash]CHCF have been studied, investigating the kinetics and the products of the reactions of the two compounds with Cl atoms, OH radicals, OD radicals, and O. FTIR smog chamber experiments measured: k(Cl + Z-CFCH[double bond, length as m-dash]CHCF) = (2.59 ± 0.47) × 10, k(Cl + E-CFCH[double bond, length as m-dash]CHCF) = (1.36 ± 0.27) × 10, k(OH + Z-CFCH[double bond, length as m-dash]CHCF) = (4.21 ± 0.62) × 10, k(OH + E-CFCH[double bond, length as m-dash]CHCF) = (1.72 ± 0.42) × 10, k(OD + Z-CFCH[double bond, length as m-dash]CHCF) = (6.94 ± 1.25) × 10, k(OD + E-CFCH[double bond, length as m-dash]CHCF) = (5.61 ± 0.98) × 10, k(O + Z-CFCH[double bond, length as m-dash]CHCF) = (6.25 ± 0.70) × 10, and k(O + E-CFCH[double bond, length as m-dash]CHCF) = (4.14 ± 0.42) × 10 cm molecule s in 700 Torr of air/N/O diluents at 296 ± 2 K. E-CFCH[double bond, length as m-dash]CHCF reacts with Cl atoms to give CFCHClC(O)CF in a yield indistinguishable from 100%. Z-CFCH[double bond, length as m-dash]CHCF reacts with Cl atoms to give (95 ± 10)% CFCHClC(O)CF and (7 ± 1)% E-CFCH[double bond, length as m-dash]CHCF. CFCHClC(O)CF reacts with Cl atoms to give the secondary product CFC(O)Cl in a yield indistinguishable from 100%, with the observed co-products C(O)F and CFOCF. The main atmospheric fate for Z- and E-CFCH[double bond, length as m-dash]CHCF is reaction with OH radicals. The atmospheric lifetimes of Z- and E-CFCH[double bond, length as m-dash]CHCF are estimated as 27 and 67 days, respectively. IR absorption cross sections are reported and the global warming potentials (GWPs) of Z- and E-CFCH[double bond, length as m-dash]CHCF for the 100 year time horizon are calculated to be GWP = 2 and 7, respectively. This study provides a comprehensive description of the atmospheric fate and impact of Z- and E-CFCH[double bond, length as m-dash]CHCF.

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“…With the experimental solar actinic flux at sea level in the atmosphere, the maximal photolysis rate coefficient of C5 was calculated to be J max = 8.3 × 10 –5 s –1 assuming a uniform quantum efficiency. The observed J max is 1.5 × 10 –4 s –1 for the analogous C6 molecule. , It is worth noting that the rate of photolysis of acetone is much lower (ca. 1–3 × 10 –7 s –1 ) even for the upper troposphere …”

Section: Resultsmentioning

confidence: 93%

Atmospheric Chemistry of Perfluoro-3-methyl-2-butanone [CF₃C(O)CF(CF₃)₂]: Photodissociation and Reaction with OH Radicals

Hou

Wang

2018

J. Phys. Chem. A

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Perfluoro-3-methyl-2-butanone (CF 3 C(O)CF(CF 3 ) 2 , abbreviated as C5) is a potentially excellent fire suppression alternative to halons and a promising dielectric gas for SF 6 replacement. As a prototypical perfluorinated asymmetrical ketone, photodissociation and reaction with hydroxyl radicals of C5 have been investigated theoretically to gain insights into its atmospheric chemistry and environmental impact. C5 has a broad UV absorption band in the range 260−360 nm with a maximum at 302 nm and the maximal photolysis rate coefficient is 8.3 × 10 −5 s −1 . Photoexcitation from S 0 through the perpendicular n → π* transition produces the excited S 1 species, which can either dissociate straightforwardly via the bifurcated α-CC bond cleavage or be trickled down to T 1 via the S 1 /T 1 intersystem crossing (ISC) pathway. In the Franck−Condon region of the S 1 surface, the long-lived S 1 species exists and the slow ISC pathway is dominant, followed by the α-cleavage through T 1 barriers to form perfluoroalkyl and perfluoroacetyl radicals. While the excitation energy exceeds 286 nm, the direct dissociation of C5 though the S 1 barriers takes over before the ISC occurs. Several pathways for regeneration of the ground-state S 0 from S 1 and T 1 via seams of crossing or internal conversion were revealed. The C5 + OH reaction occurs via direct carbonyl addition mechanism followed by the rapid displacement of one of the alkyl groups. Although it can be accelerated considerably by the H 2 O-mediated catalysis or the intercepted vibrationally excited quantum states in the hot S 0 *, the degradation of C5 by OH radicals is too slow to compete with the photolysis pathways.

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Photolysis study of fluorinated ketones under natural sunlight conditions

Abstract: UV and IR spectra of CF3COCH3 and CF3COC2H5 are provided, with photolysis being their dominant fate in the atmosphere.

Cited by 9 publications

References 24 publications

Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Atmospheric chemistry of Z- and E-CF₃CHCHCF₃

Atmospheric Chemistry of Perfluoro-3-methyl-2-butanone [CF₃C(O)CF(CF₃)₂]: Photodissociation and Reaction with OH Radicals

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Photolysis study of fluorinated ketones under natural sunlight conditions

Abstract: UV and IR spectra of CF3COCH3 and CF3COC2H5 are provided, with photolysis being their dominant fate in the atmosphere.

Cited by 9 publications

References 24 publications

Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone

Atmospheric chemistry of Z- and E-CF3CHCHCF3

Atmospheric Chemistry of Perfluoro-3-methyl-2-butanone [CF3C(O)CF(CF3)2]: Photodissociation and Reaction with OH Radicals

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Product

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Atmospheric chemistry of Z- and E-CF₃CHCHCF₃

Atmospheric Chemistry of Perfluoro-3-methyl-2-butanone [CF₃C(O)CF(CF₃)₂]: Photodissociation and Reaction with OH Radicals