The High Pressure Range of the Addition of OH to C2H2 and C2H4

Fülle, D.; Hamann, Hendrik F.; Hippler, H.; Jänsch, C.P.

doi:10.1002/bbpc.199700004

Cited by 50 publications

(130 citation statements)

References 47 publications

Supporting

Mentioning

100

Contrasting

Unclassified

Order By: Relevance

“…However, the experimental values are for temperatures ranging from about 550 to 800 K. A direct comparison of the predicted and observed temperature-dependent equilibrium constants, as in Figure 4, provides a better indication of the accuracy of the theoretical predictions. The present predictions are seen to be in remarkable agreement with the experimental results of Diau and Lee, 49 while the order of magnitude discrepancy with the data of Hippler and co-workers 51 suggests some shortcoming in that work.…”

Section: Resultssupporting

confidence: 87%

“…The experimental studies of Diau and Lee 49 and of Hippler and co-workers 51 have yielded estimated reaction enthalpies of -30.2 ( 0.5 and -29.4 ( 1.4 kcal/mol, respectively. These values are considerably lower than the present 0 K estimate of -27.0 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“…36,37,51 The high-pressure addition rate constant for C 2 H 4 + OH was generally found to decrease slightly with increasing temperature in the 100-600 K range, with measured Arrhenius activation energies ranging from -2.3 to 0.0 kcal/ mol. 23,31,36,43,51,53 Lower-temperature studies have been limited to Leone and co-workers' 53 study over the temperature range from 96 to 296 K using the pulsed Laval nozzle technique. Although relatively low pressures were employed in this study (e.g., less than 1 Torr for the lower temperatures), it was argued that the results still pertained to the high-pressure limit due to the increase in the lifetime of the complex with decreasing temperature.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

et al. 2007

View full text Add to dashboard Cite

A two transition state model is applied to the study of the addition of hydroxyl radical to ethylene. This reaction serves as a prototypical example of a radical-molecule reaction with a negative activation energy in the high-pressure limit. The model incorporates variational treatments of both inner and outer transition states. The outer transition state is treated with a recently derived long-range transition state theory approach focusing on the longest-ranged term in the potential. High-level quantum chemical estimates are incorporated in a variational transition state theory treatment of the inner transition state. Anharmonic effects in the inner transition state region are explored with direct phase space integration. A two-dimensional master equation is employed in treating the pressure dependence of the addition process. An accurate treatment of the two separate transition state regions at the energy and angular momentum resolved level is essential to the prediction of the temperature dependence of the addition rate. The transition from a dominant outer transition state to a dominant inner transition state is predicted to occur at about 130 K, with significant effects from both transition states over the 10 to 400 K temperature range. Modest adjustment in the ab initio predicted inner saddle point energy yields theoretical predictions which are in quantitative agreement with the available experimental observations. The theoretically predicted capture rate is reproduced to within 10% by the expression [4.93 × 10 -12 (T/298) -2.488 exp(-107.9/RT) + 3.33 × 10 -12 (T/298) 0.451 exp(117.6/RT); with R ) 1.987 and T in K] cm 3 molecules -1 s -1 over the 10-600 K range.

show abstract

Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The rate constants of this reaction display a typical negative temperature dependence. This is also the case-but somewhat weaker-for the relaxation data (also included in Figure 5), which show an overall good agreement with the data of Hippler et al [39] The decreasing deviation between relaxation data and rate constants for lower temperatures we attribute to the fact that the reaction, being in the low-pressure or fall-off range at high temperatures, may come closer to the high-pressure limit at the lowest temperatures. A simple and straightforward interpretation for the negative temperature dependence employing the concepts outlined is illustrated in Figure 6 for the example reaction OH + ethylene.…”

Section: Chemical Kinetics In Laval Nozzle Expansionssupporting

confidence: 80%

“…*: Secondorder rate constants measured via v = 1 relaxation of OH. Also shown are data of Fulle et al [39] together with a rate constant calculation based upon SACM theory. [39] b) Second-order rate constants for the association reaction of OH with ethylene (C 2 H 4 ).…”

Section: Molecular Collisional Energy Transfer At Low Temperaturesmentioning

confidence: 97%

Kinetics in Cold Laval Nozzle Expansions: From Atmospheric Chemistry to Oxidation of Biomolecules in the Gas Phase

Hansmann

Abel

2007

ChemPhysChem

View full text Add to dashboard Cite

New developments and recent applications of pulsed and miniaturised Laval nozzle technology allowing many gas-phase molecular processes to be studied at very low temperatures are highlighted. In the present Minireview we focus on molecular energy transfer and reactions of molecular radicals (e.g. OH) with neutral molecules. We show that with the combination of pulsed laser photolysis and sensitive laser-induced fluorescence detection a large number of fast reactions of radicals with more or less complex neutral molecules can be measured in Laval nozzle expansions nowadays. It is also demonstrated that collisional energy transfer of neutral molecules can be measured via kinetically controlled selective fluorescence (KCSF) excitation down to 58 Kelvin. Finally, we show that even the primary steps in the oxidation of biomolecules or biomolecular building blocks initiated by OH radicals can be followed at low temperatures. The temperature dependence of the measured rate constants is the key for an understanding of the underlying molecular mechanisms and the Laval nozzle expansion provides a unique environment for these measurements. The experimental finding that many reactions between radicals and neutral species can be rapid at low temperatures are discussed in terms of pre-reactive complexes formed in the overall complex forming bimolecular reactions.

show abstract

Kinetics of the reaction of OH radicals with acetylene in 25–8000 torr of air at 296 K

Sørensen

Kaiser

Hurley

et al. 2003

Int J of Chemical Kinetics

View full text Add to dashboard Cite

Relative rate techniques were used to study the kinetics of the reaction of OH radicals with acetylene at 296 K in 25-8000 Torr of air, N 2 /O 2 , or O 2 diluent. Results obtained at total pressures of 25-750 Torr were in good agreement with the literature data. At pressures >3000 Torr, our results were substantially (∼35%) lower than that reported previously. The kinetic data obtained over the pressure range 25-8000 Torr are well described (within 15%) by the Troe expression using k o = (2.92 ± 0.55) × 10 −30 cm 6 molecule −2 s −1 , k ∞ = (9.69 ± 0.30) × 10 −13 cm 3 molecule −1 s −1 , and F c = 0.60. At 760 Torr total pressure, this expression gives k OH+C 2 H 2 = 8.49 × 10 −13 cm molecule −1

show abstract

The High Pressure Range of the Addition of OH to C₂H₂ and C₂H₄

Cited by 50 publications

References 47 publications

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

Kinetics in Cold Laval Nozzle Expansions: From Atmospheric Chemistry to Oxidation of Biomolecules in the Gas Phase

Kinetics of the reaction of OH radicals with acetylene in 25–8000 torr of air at 296 K

Contact Info

Product

Resources

About