A theoretical analysis of the reaction between ethyl and molecular oxygen

Miller, James A.; Klippenstein, Stephen J.; Robertson, Struan H.

doi:10.1016/s0082-0784(00)80544-5

Cited by 107 publications

(222 citation statements)

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“…The rate coefficients and product distributions themselves differ relatively little from those given in Ref. [18], i.e. the changes in symmetry number and E 02 tend to cancel over fairly wide ranges of temperature and pressure.…”

Section: Theorymentioning

confidence: 52%

“…All the experimental results with which we compared our predictions in Ref. [18] are contained in the figures of this arti- cle, although we do not comment on them further here.…”

Section: Theorymentioning

confidence: 99%

“…Baldwin et al [17] have studied the product distribution of the C 2 H 5 + O 2 reaction in the temperature range 673 K ≤ T ≤ 813 K. They determined that the only carbon-containing products were ethylene and ethylene oxide and that their relative yields were C 2 H 4 :C 2 H 4 O ≈ 100, independent of pressure. To compare with this result we have calculated the relative product yields at the collisionless limit (an accurate approximation at these temperatures [18]) using JT-T (microcanonical, J-resolved variational transition-state theory with tunneling) [23], in which both total energy E and the total angular momentum quantum number J are conserved from transition state to transition state, and there is a different, variationally determined, dividing surface for TS-1 for every E, J combination. In this calculation all the possible rearrangements shown in Fig.…”

Section: Theorymentioning

confidence: 99%

“…Because ethane is the simplest alkane to exhibit the behavior discussed above, ethyl (C 2 H 5 ) has become the prototype alkyl radical, and its reaction with O 2 has been studied extensively in the laboratory [8,[10][11][12][13][14][15][16][17]. Theoretical investigations have also begun to appear [7,8,[18][19][20][21][22]. An important question addressed in the theoretical work concerns the exact nature of reaction (R4).…”

Section: Introductionmentioning

confidence: 99%

“…In a previous article [18] we used DFT-B3LYP and a G2-like method to characterize the potential energy surface (PES), RRKM theory to calculate microcanonical rate coefficients, and solutions to the time-dependent master equation to characterize the rate and product distribution of the C 2 H 5 + O 2 reaction over wide ranges of temperature and pressure. Because of space limitations in the Combustion Symposium proceedings, we limited our discussion there to comparing our results with experiment and to describing the three different regimes of the reaction.…”

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confidence: 99%

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The reaction between ethyl and molecular oxygen II: Further analysis

Miller

Klippenstein

2001

Int J of Chemical Kinetics

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The present investigation is a rather substantial extension and elaboration of our previous work on the same reaction. In this article we accomplish four primary objectives:1. We show quantitatively how sensitive the high-temperature rate coefficient k(T) is to E 02 , the threshold energy of the transition state for direct molecular elimination of HO 2 from ethylperoxy radical (C 2 H 5 O 2 ), thus deducing a value of E 02 = −3.0 kcal/mol (measured from reactants). 2. We derive the result that k 0 (T) ≈ k ∞ (T) in the high-temperature regime, where k 0 (T) is the zero-pressure rate coefficient, and k ∞ (T) is the infinite-pressure rate coefficient for the bimolecular channel. 3. Most importantly, we discuss the three different regimes of the reaction (low-temperature, transition, and high-temperature) in terms of the eigenvectors and eigenvalues of G , the transition matrix of the master equation. The transition regime is shown to be a region of avoided crossing between the two chemically significant eigenvalue curves in which the thermal rate coefficient k(T , p) jumps from one eigenvalue to the other. This jump is accompanied by a "mixing" of the corresponding eigenvectors, through which both eigenvectors deplete the reactant. The onset of the high-temperature regime is triggered by reaching the "stabilization limit" of the ethylperoxy adduct, a limit that is induced by a shift in equilibrium of the stabilization reaction. Our identification of the prompt and secondary HO 2 formed by the reaction with these eigenvalue/eigenvector pairs leads to good agreement between theory and the experiments of Clifford et al. (J Phys Chem A 2000, 104, 11549-11560). 4. Lastly, we describe the master equation results in terms of a set of elementary reactions and phenomenological rate coefficients.

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Section: Theorymentioning

confidence: 52%

“…All the experimental results with which we compared our predictions in Ref. [18] are contained in the figures of this arti- cle, although we do not comment on them further here.…”

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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The reaction between ethyl and molecular oxygen II: Further analysis

Miller

Klippenstein

2001

Int J of Chemical Kinetics

Self Cite

127

217

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Exploring Multiple Reaction Paths to a Single Product Channel

Osborn

2008

Advances in Chemical Physics

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Hydrogen Migrations in Alkylcycloalkyl Radicals: Implications for Chain‐Branching Reactions in Fuels

Davis

Tangprasertchai

Francisco

2012

Chemistry A European J

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A thorough understanding of the oxidation chemistry of cycloalkanes is integral to the development of alternative fuels and improving current fuel performance. An important class of reactions essential to this chemistry is the hydrogen migration; however, they have largely been omitted from the literature for cycloalkanes. The present work investigates all of the hydrogen migration reactions available to methylcyclopentane, ethylcyclopentane, methylcyclohexane, and ethylcyclohexane. The kinetic and thermodynamic parameters have been studied by a combination of computational methods and compared to their corresponding n-alkyl and methylalkyl counterparts to determine the effect that the cycloalkane ring has on these reactions. In particular, although the alkylcycloalkyl activation energies for the dominant 1,4, 1,5, and 1,6 H-migration are higher than in n-alkyl and methylalkyl radicals, because several of the rotors needed to form the transition state are locked into place as part of the cycloalkane ring, the A-factors are higher for the alkylcycloalkyl reactions, making the rates closer to the noncyclic systems, at higher temperatures. The results presented here suggest that the relative importance of each H-migration pathway differs from the trends predicted by either the n-alkyl or methylalkyl radical systems. Of particular interest is the observation that since the barrier height of the 1,4 H-migration is only 3-5 kcal mol(-1) higher than the 1,5 H-migration in the methyl and ethylcycloalkyl radicals, compared to a difference of roughly 7 kcal mol(-1) in similar reactions for both the n-alkyl and methylalkyl radicals, the 1,4 H-migrations in alkylcycloalkyl radicals will be more important in the overall mechanism than would be predicted based on the n-alkyl and methylalkyl radicals. These results have important combustion model implications, particularly for fuels with high cycloalkane content.

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A theoretical analysis of the reaction between ethyl and molecular oxygen

Cited by 107 publications

References 29 publications

The reaction between ethyl and molecular oxygen II: Further analysis

The reaction between ethyl and molecular oxygen II: Further analysis

Exploring Multiple Reaction Paths to a Single Product Channel

Hydrogen Migrations in Alkylcycloalkyl Radicals: Implications for Chain‐Branching Reactions in Fuels

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