Free radical addition to olefins. Part 5. - Addition of difluorobromomethyl radicals to trifluoroethylene and ethylene

J. M. Tedder; J. C. Walton

doi:10.1039/TF9706601135

Free radical addition to olefins. Part 5. - Addition of difluorobromomethyl radicals to trifluoroethylene and ethylene

J. M. Tedder^*, J. C. Walton

^*Corresponding author for this work

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Abstract

The photochemical reaction of CF₂Br₂ with CHF=CF ₂ and CH₂=CH₂ has been examined in a series of gas-phase experiments. A mechanism for the radical chain addition which takes place is proposed. The variation in the rate of formation of the termination products, CF₂BrCF₂Br and CF₂BrCHFCF ₂CF₂Br, with reactant concentration is explained if five important termination reactions are taken into account and a long-lived excited state of the CF₂Br₂ is accepted. Arrhenius parameters for the addition of CF₂Br· radicals to the olefins have been derived: CF₂Br·+ E→CF₂BrE· (2) CF ₂Br·+CF₂Br·→ CF₂BrCF ₂Br (4) k₂/k₄^1/2 (addition to=CHF)=(1.2±0.3)×10² exp (-3300±200/RT), k ₂/k₄^1/2 (addition to=CF₂)=(2. 0±0.3)×10² exp (-4400±200/RT), k ₂/k₄^1/2 (addition to=CH₂)=(2. 5±0.5) exp (-1000/RT). A factors are in 1.^1/2 mol ^-1/2 s^-1/2; activation energies in kcal/mol; R=1.99 cal deg.^-1 mol^-1; 1 cal=4.184 J.

Original language	English
Pages (from-to)	1135-1144
Number of pages	10
Journal	Transactions of the Faraday Society
Volume	66
DOIs	https://doi.org/10.1039/TF9706601135
Publication status	Published - 1 Jan 1970

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@article{3a27e531401e4d709aeb384af5d16081,

title = "Free radical addition to olefins. Part 5. - Addition of difluorobromomethyl radicals to trifluoroethylene and ethylene",

abstract = "The photochemical reaction of CF2Br2 with CHF=CF 2 and CH2=CH2 has been examined in a series of gas-phase experiments. A mechanism for the radical chain addition which takes place is proposed. The variation in the rate of formation of the termination products, CF2BrCF2Br and CF2BrCHFCF 2CF2Br, with reactant concentration is explained if five important termination reactions are taken into account and a long-lived excited state of the CF2Br2 is accepted. Arrhenius parameters for the addition of CF2Br· radicals to the olefins have been derived: CF2Br·+ E→CF2BrE· (2) CF 2Br·+CF2Br·→ CF2BrCF 2Br (4) k2/k41/2 (addition to=CHF)=(1.2±0.3)×102 exp (-3300±200/RT), k 2/k41/2 (addition to=CF2)=(2. 0±0.3)×102 exp (-4400±200/RT), k 2/k41/2 (addition to=CH2)=(2. 5±0.5) exp (-1000/RT). A factors are in 1.1/2 mol -1/2 s-1/2; activation energies in kcal/mol; R=1.99 cal deg.-1 mol-1; 1 cal=4.184 J.",

author = "Tedder, {J. M.} and Walton, {J. C.}",

year = "1970",

month = jan,

day = "1",

doi = "10.1039/TF9706601135",

language = "English",

volume = "66",

pages = "1135--1144",

journal = "Transactions of the Faraday Society",

issn = "0014-7672",

publisher = "Faraday Division of the Chemical Society",

}

TY - JOUR

T1 - Free radical addition to olefins. Part 5. - Addition of difluorobromomethyl radicals to trifluoroethylene and ethylene

AU - Tedder, J. M.

AU - Walton, J. C.

PY - 1970/1/1

Y1 - 1970/1/1

N2 - The photochemical reaction of CF2Br2 with CHF=CF 2 and CH2=CH2 has been examined in a series of gas-phase experiments. A mechanism for the radical chain addition which takes place is proposed. The variation in the rate of formation of the termination products, CF2BrCF2Br and CF2BrCHFCF 2CF2Br, with reactant concentration is explained if five important termination reactions are taken into account and a long-lived excited state of the CF2Br2 is accepted. Arrhenius parameters for the addition of CF2Br· radicals to the olefins have been derived: CF2Br·+ E→CF2BrE· (2) CF 2Br·+CF2Br·→ CF2BrCF 2Br (4) k2/k41/2 (addition to=CHF)=(1.2±0.3)×102 exp (-3300±200/RT), k 2/k41/2 (addition to=CF2)=(2. 0±0.3)×102 exp (-4400±200/RT), k 2/k41/2 (addition to=CH2)=(2. 5±0.5) exp (-1000/RT). A factors are in 1.1/2 mol -1/2 s-1/2; activation energies in kcal/mol; R=1.99 cal deg.-1 mol-1; 1 cal=4.184 J.

AB - The photochemical reaction of CF2Br2 with CHF=CF 2 and CH2=CH2 has been examined in a series of gas-phase experiments. A mechanism for the radical chain addition which takes place is proposed. The variation in the rate of formation of the termination products, CF2BrCF2Br and CF2BrCHFCF 2CF2Br, with reactant concentration is explained if five important termination reactions are taken into account and a long-lived excited state of the CF2Br2 is accepted. Arrhenius parameters for the addition of CF2Br· radicals to the olefins have been derived: CF2Br·+ E→CF2BrE· (2) CF 2Br·+CF2Br·→ CF2BrCF 2Br (4) k2/k41/2 (addition to=CHF)=(1.2±0.3)×102 exp (-3300±200/RT), k 2/k41/2 (addition to=CF2)=(2. 0±0.3)×102 exp (-4400±200/RT), k 2/k41/2 (addition to=CH2)=(2. 5±0.5) exp (-1000/RT). A factors are in 1.1/2 mol -1/2 s-1/2; activation energies in kcal/mol; R=1.99 cal deg.-1 mol-1; 1 cal=4.184 J.

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DO - 10.1039/TF9706601135

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SN - 0014-7672

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JO - Transactions of the Faraday Society

JF - Transactions of the Faraday Society

ER -

Free radical addition to olefins. Part 5. - Addition of difluorobromomethyl radicals to trifluoroethylene and ethylene

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