The Photolysis of Ketene in the Presence of Hydrogen

Gesser, H. D.; Steacie, E. W. R.

doi:10.1139/v56-014

Cited by 36 publications

(25 citation statements)

References 7 publications

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“…Several reviews [9-111 of the extensive literature on this reaction concur in the conclusion that while the measurements of the reaction in the forward or the reverse direction are in concordance, there is a large discrepancy between the reported values for k , and k -, and the equilibrium constant, Kl,-l, with k l / k -* = 4Kl,-, near 375 K, the lowest temperature at which measurements in the reverse direction have been made. The lowesttemperature measurements of k -l were those of Gesser and Steacie [12] (372 < T/K < 480). More recent measurements include those of Moller et al [13] in a shock tube (1070 < T/K < 2320,30 < p/torr < 121); of Baldwin et al [14] at 753 K, relative to reaction of CH3 + CH3 -+ CzH6 (kI2); and of Marshall and Shahkar [15] by a novel technique not involving a relative measurement (584 < T/K < 671,5 < p/torr < 26).…”

Section: Resultsmentioning

confidence: 97%

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

Cohen

1991

Int J of Chemical Kinetics

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The thermochemical kinetics formulation of conventional transition state theory has been applied to metathesis reactions of H atoms with a series of alkanes in order to provide a sound framework for the intercomparison of experimental data, and also to extrapolate rate coefficients to temperature regimes that may lie beyond the range of experiments. The calculations require a value for the rate coefficient at some temperature, necessitating a discussion of the extant experimental data and their reliability. The procedures are described, the results of the calculations are presented, and their agreement with experimental data (for methane, ethane, propane, butane, pentane, isobutane, cyclopropane, cyclohexane, neopentane, neooctane, and 2,2,3-trimethylbutane) is discussed. A general expression for reactions of H with large (more than 4 carbons) alkanes is proposed: K(T) = 5.4 x 103n,TZ0 exp(-3540/T) + 4.7 x 103nsTZZ exp(-2640/T) + 3.7 x 103n,TZ0 exp(-970/T), where n,,, ns, and n, are the numbers of primary, secondary, and tertiary H atoms available for abstraction.

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Section: Resultsmentioning

confidence: 97%

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

Cohen

1991

Int J of Chemical Kinetics

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“…obtain absolute k 2 values from five earlier studies [15][16][17]19,21]. Their evaluation, transformed using Eq.…”

Section: Figurementioning

confidence: 99%

“…With new experimental results and theory, they solved this discrepancy. Kurosaki and Takayanagi [73] were interested in explaining a measured kinetic isotope effect at 5 K whereas Schatz et al [60] and Truhlar and coworkers [64] wanted to explain higher temperature kinetic isotope effects, measured many years before by a number of investigators [15][16][17]19]. Certain other studies have been mostly concerned with developing theoretical methods for extrapolating fits from H + CH 4 to H with substituted and saturated hydrocarbon molecules [13,68].…”

Section: Figurementioning

confidence: 99%

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Rate constants for H + CH₄, CH₃ + H₂, and CH₄ dissociation at high temperature

Sutherland¹,

Su²,

Michael³

2001

Int J of Chemical Kinetics

142

143

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The Laser Photolysis-Shock Tube technique coupled with H-atom atomic resonance absorption spectrometry has been used to study the reaction, H + CH 4 → CH 3 + H 2 , over the temperature range, 928-1697 K. Shock-tube studies on the reverse of this reaction, CH 3 + H 2 → H + CH 4 , using CH 3 I dissociation in the presence of H 2 yielded H-atom formation rates and rate constants for the reverse process over the temperature range, 1269-1806 K. These results were transformed (using well-established equilibrium constants) to the forward direction. The combined results for H + CH 4 can be represented by an experimental three parameter expression, k = 6.78 × 10 −21 T 3.156 exp(−4406 K/T ) cm 3 molecule −1 s −1 (348-1950 K) that was evaluated from the present work and seven previous studies. Using this evaluation, disagreements between previously reported values for the dissociation of CH 4 could be reconciled. The thermal decomposition of CH 4 was then studied in Kr bath gas. The dissociation results agreed with the earlier studies and were theoretically modeled with the Troe formalism. The energy transfer parameter necessary to explain both the present results and those of Kiefer and Kumaran (J Phys Chem 1993, 97, 414) is, − E all /cm −1 = 0.3323 T 0.7 . The low temperature data on the reverse reaction, H + CH 3 (in He) from Brouard et al. (J Phys Chem 1989, 93, 4047) were also modeled with the Troe formalism. Lastly, the rate constant for H + CH 4 was theoretically calculated using conventional transition state theory with Eckart tunneling corrections. The potential energy surface used was from Kraka et al. (J Chem Phys 1993, 99, 5306) and the derived T-dependence with this method agreed almost perfectly with the experimental evaluation.

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“…The data of Majury and Steacie for 400 < T < 570 O K are generally accepted as reliable (10)(11)(12), although there seems to be no clear reason to reject the data of Davison and Burton (7) or Anderson and Taylor (8). However all of the determinations of the rate coefficient for reaction 5 have been made at temperatures below 600 O K , and there is only one estimate (9) of k, above 600 OK.…”

Section: Introductionmentioning

confidence: 99%

The Rate Coefficient for CH₃ + H₂ → CH₄ + H Measured in Reflected Shock Waves; A Non-Arrhenius Reaction

Clark¹,

Dove²

1973

Can. J. Chem.

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Dynamic sampling of reacting gas mixtures behind reflected shock waves has been used to determine the concentration vs. time profiles of the products of the recombination chain reactions of methyl radicals in the presence of molecular H2. The radicals were produced by the rapid pyrolysis of azomethane. By analysis of profiles from experiments in the temperature range 1272–1370°K we have deduced a value of the rate coefficient of reaction 5: CH3 + H2 → CH4 + H.[Formula: see text]It is shown that although this value of k5 does not lie on the Arrhenius line drawn through lower temperature data, it does lie close to the upward curved Arrhenius plot of values of k5 calculated by the B.E.B.O. transition state method. Taking a mean activation energy calculated by the B.E.B.O. method, our results suggest the following description for k5 over the temperature range 1200 to 2000°K:[Formula: see text]

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The Photolysis of Ketene in the Presence of Hydrogen

Abstract: ?'he photolysis of ketene in the presence of hydrogen has been investigated in the temperature range -40" to 207'C. The main products are CO, C?H4, C2H6, and CHr, with some methyl ethyl ltetone a t the higher temperatures.

Cited by 36 publications

References 7 publications

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

Rate constants for H + CH₄, CH₃ + H₂, and CH₄ dissociation at high temperature

The Rate Coefficient for CH₃ + H₂ → CH₄ + H Measured in Reflected Shock Waves; A Non-Arrhenius Reaction

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The Photolysis of Ketene in the Presence of Hydrogen

Abstract: ?'he photolysis of ketene in the presence of hydrogen has been investigated in the temperature range -40" to 207'C. The main products are CO, C?H4, C2H6, and CHr, with some methyl ethyl ltetone a t the higher temperatures.

Cited by 36 publications

References 7 publications

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes

Rate constants for H + CH4, CH3 + H2, and CH4 dissociation at high temperature

The Rate Coefficient for CH3 + H2 → CH4 + H Measured in Reflected Shock Waves; A Non-Arrhenius Reaction

Contact Info

Product

Resources

About

Rate constants for H + CH₄, CH₃ + H₂, and CH₄ dissociation at high temperature

The Rate Coefficient for CH₃ + H₂ → CH₄ + H Measured in Reflected Shock Waves; A Non-Arrhenius Reaction