Quantum chemical investigations on the dynamics of hydrogen halide elimination from vinyl-halides: influence of the molecular environment

Kunsági‐Máté, Sándor; Végh, Eszter; Nagy, Géza; Kollár, László

doi:10.1016/j.cplett.2004.02.075

Cited by 7 publications

(7 citation statements)

References 34 publications

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“…Treatment of the vinyl fluoride dissociation introduces a further complication through the occurrence of two paths for the process, a three-center elimination to vinylidene which quickly reverts to acetylene, reaction (2) and a four-center elimination giving acetylene directly, reaction (3). 18,19…”

Section: Introductionmentioning

confidence: 99%

“…This complication does, however, add a further reason for undertaking a study of the thermal dissociation of vinyl fluoride. The branching between the two routes for this has been discussed both theoretically [18][19][20] and experimentally 20 using molecular-beam laser photolysis, and it seems that both must be heavily involved, but no evaluation of the thermal ratio has appeared.…”

Section: Introductionmentioning

confidence: 99%

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Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride

Kiefer

Sivaramakrishnan

et al. 2007

Phys. Chem. Chem. Phys.

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This paper reports measurements of the thermal dissociation of 1,1-difluoroethane in the shock tube. The experiments employ laser-schlieren measurements of rate for the dominant HF elimination using 10% 1,1-difluoroethane in Kr over 1500-2000 K and 43 < P < 424 torr. The vinyl fluoride product of this process then dissociates affecting the late observations. We thus include a laser schlieren study (1717-2332 K, 75 < P < 482 torr in 10 and 4% vinyl fluoride in Kr) of this dissociation. This latter work also includes a set of experiments using shock-tube time-of-flight mass spectrometry (4% vinyl fluoride in neon, 1500-1980 K, 500 < P < 1300 torr). These time-of-flight experiments confirm the theoretical expectation that the only reaction in vinyl fluoride is HF elimination. The dissociation experiments are augmented by laser schlieren measurements of vibrational relaxation (1-20% C(2)H(3)F in Kr, 415-1975 K, 5 < P < 50 torr, and 2 and 5% C(2)H(4)F(2) in Kr, 700-1350 K, 6 < P < 22 torr). These experiments exhibit very rapid relaxation, and incubation delays should be negligible in dissociation. An RRKM model of dissociation in 1,1-difluoroethane based on a G3B3 calculation of barrier and other properties fits the experiments but requires a very large DeltaE(down) of 1600 cm(-1), similar to that found in a previous examination of 1,1,1-trifluoroethane. Dissociation of vinyl fluoride is complicated by the presence of two parallel HF eliminations, both three-center and four-center. Structure calculations find nearly equal barriers for these, and TST calculations show almost identical k(infinity). An RRKM fit to the observed falloff again requires an unusually large DeltaE(down) and the experiments actually support a slightly reduced barrier. These large energy-transfer parameters now seem routine in these large fluorinated species. It is perhaps a surprising result for which there is as yet no explanation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride

Kiefer

Sivaramakrishnan

et al. 2007

Phys. Chem. Chem. Phys.

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show abstract

“…Our recent examinations regarding some special reactions of vinyl bromide [17] and of the whole vinyl-halogenid serie [18] pointed out the decisive role of vibrational energy distribution and induced redistribution on the dissociation reaction rate. Therefore, the methodology described there [17,18] was followed to examine the backgrounds of the unexpected reactivity difference of 1, 2 and 3 predicted by the experiments.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the methodology described there [17,18] was followed to examine the backgrounds of the unexpected reactivity difference of 1, 2 and 3 predicted by the experiments.…”

Section: Resultsmentioning

confidence: 99%

“…This is accomplished by adding a random force (to model the effect of collisions) and a frictional force (to model dissipative losses) to each atom at each time step during the simulation. Application of this method for the investigation of the C-X (X=F, Cl, Br, I) bond-breaking of halo-ethene was described elsewhere recently [17,18]. The results of the Langevin dynamic calculations show the decrease of vibrational energy localized on the idodovinyl site (reduced to 12% and 9% in case of 2 and 3, respectively).…”

Section: Vibrational Energy Distribution As Ddynamict Parameter Of Thmentioning

confidence: 96%

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Unexpected reactivity difference between iodo-alkene moieties of steroids possessing remote lactame or cycloalkane structural units: a theoretical approach

Kunsági‐Máté

Skoda‐Földes

Szepes

et al. 2004

Journal of Biochemical and Biophysical Methods

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Temperature-dependent solvent effect on the kinetic energy distribution on p-cresol molecule as building block of calixarene capsules

Kunsági‐Máté

Bakonyi

Kollár

et al. 2009

J Incl Phenom Macrocycl Chem

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Quantum chemical investigations on the dynamics of hydrogen halide elimination from vinyl-halides: influence of the molecular environment

Cited by 7 publications

References 34 publications

Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride

Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride

Unexpected reactivity difference between iodo-alkene moieties of steroids possessing remote lactame or cycloalkane structural units: a theoretical approach

Temperature-dependent solvent effect on the kinetic energy distribution on p-cresol molecule as building block of calixarene capsules

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