The potential of hydrofluoroethers to replace CFCs, HCFCs and PFCs

Sekiya, Akira; Misaki, Susumu

doi:10.1016/s0022-1139(99)00162-1

Cited by 209 publications

(187 citation statements)

References 4 publications

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“…[1][2][3] Hydrofluoroethers (HFEs) have been developed as third-generation alternative compounds to CFCs and are used in various industrial applications. [4][5][6] These compounds are analogous to HFCs but contain an ether (ÀOÀ) linkage, which has no ODP. [7,8] Prior to its large-scale industrial use, and bearing in mind its relatively longer atmospheric lifetime, an assessment of the atmospheric chemistry and environmental impact of this compound is needed [Reaction (1)].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom

Liu

et al. 2004

ChemPhysChem

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Theoretical investigations are carried out on the reaction mechanism of the reactions of CF3OCHF2 (HFOC-125) with the OH radials and Cl atoms, as well as the heats of formation of CF3OCHF2 and CF3OCF2. The electronic structure information on the potential energy surface for each reaction is obtained at the B3LYP/6-311G(d,p) level, and energetic information is further refined by G3(MP2) theory. The direct dynamics calculation of the hydrogen abstraction reactions are also performed at the G3(MP2)//B3LYP/ 6-311G(d,p) level. The classical energy profile is corrected by interpolated single-point energies (ISPE) approach, incorporating the small-curvature tunnelling effect (SCT) calculated by the variational transition-state theory (VTST). The rate constants are in good agreement with the experimental data and are found to be k1 = 4.95 x 10(-30)T(5.40)exp(-347/T) and k2 = 1.86 x 10(-23)T(3.43)exp(-1579/T) cm3 molecule(-1)s(-1) over the temperature range 200-2000 K. The rate constants at 298 K for these two reactions are 3.38 x 10(-16) and 2.80 x 10(-17) cm3 molecule(-1)s(-1), respectively. Using group-balanced isodesmic reactions as working chemical reactions, the standard enthalpies of formation for CF3OCHF2 and CF3OCF2 are -312.3 +/- 1.0 and -257.3 +/- 1.0 kcalmol(-1), respectively, evaluated by G3(MP2) theory based on the B3LYP/6-311G(d,p) geometries. The theoretical studies provide rate constants of the title reactions and the enthalpies of the species, which are important parameters in determining the atmospheric lifetime and the feasible pathways for the loss of HFOC-125.

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Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom

Liu

et al. 2004

ChemPhysChem

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“…Partially halogenated ethers have uses both as potential replacements for chlorofluorocarbons 1 (CFCs) in a number of applications, and as quite widely used anaesthetics. 2 Consequently, studies of the kinetics of the reactions of these compounds with free radicals, especially OH, are useful, since the results aid our understanding of their atmospheric chemistry and allow their atmospheric lifetimes to be estimated.…”

Section: Introductionmentioning

confidence: 99%

Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method

Beach

Hickson

Smith

et al. 2001

Phys. Chem. Chem. Phys.

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Rate constants have been determined for the reactions of OH radicals and Cl atoms with the three partially halogenated methyl-ethyl ethers, CF 3 CH 2 OCHF 2 , CF 3 CHClOCHF 2 and CF 3 CH 2 OCClF 2 , using discharge-flow techniques to generate the OH radicals and the Cl atoms and resonance fluorescence to observe changes in their relative concentrations in the presence of added ether. For each combination of radical and ether, experiments were carried out at three temperatures between 292 and 410 K, yielding the following Arrhenius expressions for the rate constants within this range of temperature: OH + CF 3 CH 2 OCHF 2 : k = (2.0 ± 0.8) × 10 -11 exp( -2110 ± 150 K / T) cm 3 molecule -1 s -1 OH + CF 3 CHClOCHF 2 : k = (4.5 ± 1.3) × 10 -13 exp( -940 ± 100 K / T) cm 3 molecule -1 s -1 OH + CF 3 CH 2 OCClF 2 : k = (1.6 ± 0.6) × 10 -12 exp( -1100 ± 125 K / T) cm 3 molecule -1 s -1 Cl + CF 3 CH 2 OCHF 2 : k = (6.1 ± 1.4) × 10 -12 exp( -1830 ± 90 K / T) cm 3 molecule -1 s -1 Cl + CF 3 CHClOCHF 2 : k = (7.8 ± 2.6) × 10 -11 exp( -2980 ± 130 K / T) cm 3 molecule -1 s -1 Cl + CF 3 CH 2 OCClF 2 : k = (2.2 ± 0.2) × 10 -11 exp( -2700 ± 40 K / T) cm 3 molecule -1 s -1 2 Paper for PhysChemChemPhys on OH, Cl + ethersThe results are compared with those obtained previously for the same and related reactions of OH radicals and Cl atoms, and the atmospheric implications of the results are considered briefly. IntroductionPartially halogenated ethers have uses both as potential replacements for chlorofluorocarbons 1 (CFCs) in a number of applications, and as quite widely used anaesthetics. 2 Consequently, studies of the kinetics of the reactions of these compounds with free radicals, especially OH, are useful, since the results aid our understanding of their atmospheric chemistry and allow their atmospheric lifetimes to be estimated. Less directly, they assist with the interpretation of laboratory experiments that are designed to reveal the mechanisms by which these ethers break down in the atmosphere. 3 Finally, evaluation of the rate constants and activation energies for these reactions can help with the construction of structure-activity relationships. In this context, one can, for example, compare the kinetic parameters for the reactions of a given radical with the substituted ethers with those for the reactions of the same radical with the corresponding substituted alkanes where the ether linkage is absent. Alternatively, one can explore how substitution of fluorine or chlorine atoms for hydrogen atoms affects the susceptibility of the molecule to attack by, for example, OH radicals or Cl atoms.Hydrofluoroethers (HFEs) are favoured as possible CFC replacements over other halogenated ethers as they contain no chlorine, which if released as atoms can catalytically destroy stratospheric ozone. Of course, HFEs are volatile and will inevitably be released into the atmosphere during use. Their oxidation, initiated predominantly by OH radicals, will lead to the formation of fluorinated esters and fluorinated formates. 4,5 The likely i...

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“…HFEs have also been demonstrated as environmental friendly cleaning solvents for electronics. [10][11][12] Typical commercially available HFEs are isomeric mixtures of methyl nonafluorobutyl ether and methyl nonafluoroisobutyl ether (HFE 7100) and 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethylhexane (HFE 7500) shown in Scheme 1. We tested the impact of these solvents on well-characterized and commercially available organic electronic materials.…”

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confidence: 99%

Hydrofluoroethers as Orthogonal Solvents for the Chemical Processing of Organic Electronic Materials

et al. 2008

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The potential of hydrofluoroethers to replace CFCs, HCFCs and PFCs

Cited by 209 publications

References 4 publications

Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom

Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom

Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method

Hydrofluoroethers as Orthogonal Solvents for the Chemical Processing of Organic Electronic Materials

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The potential of hydrofluoroethers to replace CFCs, HCFCs and PFCs

Cited by 209 publications

References 4 publications

Theoretical Study of the Reactions of CF3OCHF2 with the Hydroxyl Radical and the Chlorine Atom

Theoretical Study of the Reactions of CF3OCHF2 with the Hydroxyl Radical and the Chlorine Atom

Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method

Hydrofluoroethers as Orthogonal Solvents for the Chemical Processing of Organic Electronic Materials

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Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom

Theoretical Study of the Reactions of CF₃OCHF₂ with the Hydroxyl Radical and the Chlorine Atom