Bond dissociation energies of selected fluorocarbons /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
[College Station, Tex.] :
Pickard,
1976.
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| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy |
| Abstract: | The gas phase reaction of 1,1-difluoroethylene with bromine was studied over the temperature range 550 to 620°K. The experimental data, derived from the early stages of reaction, were found to be consistent with the following mechanism: [Diagram in PDF]. A least squares treatment of the kinetic data yields; log(k(subscript ap)/M⁻³/²s⁻¹ ) = (7.8 ± 0.1) - (17.8 ± 0.3 )/θ, where k(subscript ap) = k₅(k₁/k₂)¹/² (k₃ /k₄ ) and θ = 2.303 RT kcal/mol. The apparent activation energy, E (subscript ap) = 17.8 ± ap 0.3 kcal/mol, was used with appropriate thermodynamic data to obtain the C-Br bond dissociation energy in the 2-bromo-1,1-difluoroethyl radical, DH°(CF₂CH₂-Br) = 6.8 ± 1 kcal/mol. This was combined with relevant data to derive the pi bond dissociation energy in 1,1- difluoroethylene, Dπ°(CH₂=CF₂) = 62.1 ± 1.5 kcal/mol. The kinetics of the gas phase reaction of 1,1 -difluoroiodoethane with hydrogen iodide were studied from 496 to 549°K for which the overall mechanism is given by [Diagram in PDF]. The rate of reaction was determined from a fourth order polynomial fit of P (subscript I₂) versus time. A least squares analysis of the resultant kinetic data yields: log (k₁/M⁻¹s⁻¹) = (11.4 ± 0.3) - (15.7 ± 0 .8 )/ θ and log (k₂/k₃ ) = (0.47 ± 0.07) + 1/θ. The observed activation energy, E₁, was combined with the assumption, E₂= 0 ± 1 kcal/mol to yield: AH°(subscript r)(1,523°K) = 15.7 ± 1 kcal/mol which leads to DH°(CH₃CF₂-I ) = 52.1 ± 1 kcal/mol.. |
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| Item Description: | "Major subject: Chemistry." Vita. |
| Physical Description: | xiii, 113 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references (leaves 103-108). |