Activation Energies of Reactions of Methyl Radicals with Organic Molecules<sup>1</sup>

Rice, F. O.; Varnerin, Robert E.

doi:10.1021/ja01606a080

Cited by 15 publications

(13 citation statements)

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“…For experiments in the lower temperature range the rate of initiation by ethane is negligible compared to the rate of initiation in pure ethylene and the term in the first square brackets in eq. [5] is not significantly greater than one. Two examples are shown in Fig.…”

Section: Resultsmentioning

confidence: 67%

“…Although rate constants for the transfer reaction with several olefins have been reported, values of the rate constant for abstraction from ethylene are conspicuously absent. Only two measurements have been reported, one relative to abstraction from acetone (4) and the other relative to acetaldehyde (5). No measurements have been reported above 833 K. Nevertheless this reaction is important in many thermal reactions of hydrocarbons over a wide range of temperatures and a reliable value for the rate constant is crucial in the evaluation of mechanisms through 'Present address: Department of Chemistry, University of Benin, Benin City, Nigeria.…”

Section: Introductionmentioning

confidence: 99%

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Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

Ahonkhai¹,

Back²

1988

Can. J. Chem.

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This paper is dedicated to Professsor J . A . Morrison S. I. AHONKHAI and M. H. BACK. Can. J. Chem. 66,578 (1988). A method is described for the measurement of relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene based on the effect of the addition of small quantities of ethane on the rates of formation of products in the thermal reactions of ethylene. The ratio of rate constants for reactions over the temperature range 673-733 K was given by the following expression: 3500 * 500 log k4lk3 = 0.0 2 0.1 + 2.3RT (R = 1.987 cal mol-I deg-I). Using a value of k4 from the literature the following expression was obtained for k3, over the same range of temperature:It was concluded that a previous measurement of k3 in a lower range of temperature was too close to the value of k4

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Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

Ahonkhai¹,

Back²

1988

Can. J. Chem.

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“…A large number of studies have been performed on acetaldehyde [30,[34][35][36][37][38][39][40][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]. In the present study, we have selected a subset of these studies to validate an updated reaction model with respect to a large variety of kinetic targets, over wide ranges of compositions and conditions.…”

Section: Validation Databasementioning

confidence: 99%

An updated reaction model for the high-temperature pyrolysis and oxidation of acetaldehyde

Mével

Chatelain

Blanquart

et al. 2018

Fuel

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Oxygenated biofuels such as fatty acid methyl esters or ethanol are incorporated in larger and larger amounts into conventional hydrocarbon fuels for use in internal combustion and jet engines. The use of these alternative fuels, along with new engine technology, results in an increased production of toxic pollutants among which aldehydes are the most abundant. The present study focuses on the kinetic modeling of acetaldehyde pyrolysis and oxidation. Based on new ignition delay-time measurements obtained in shock tube and the data from the literature, a comprehensive validation database was assembled. Available kinetic parameters for the most important chemical reactions are reviewed and an updated reaction model is proposed. The new reaction model enables reproducing most of the trends observed experimentally and constitutes an overall improvement as compared to standard detailed chemical models including Aramco 2.0, CaltechMech, and JetSurf.

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“…As a consequence, the accurate heats of reactions can be calculated and they can be combined with the barriers of forward reactions, to obtain the activation energies of the backward reactions. The reverse reactions of the β-bond cleavage denoted as (-1) in alkyl radicals are the radical additions to the C=C bond in the corresponding olefins: * It has been suggested, that hydrogen abstractions (2) can compete with addition reactions [16][17]18,19]. The competition between addition and abstraction, and the consequence for complex system modeling will be discussed.…”

Section: Introductionmentioning

confidence: 99%

Ab initio study on alkyl radical decomposition and alkyl radical addition to olefins

Viskolcz

Serés

2009

React Kinet Catal Lett

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The β bond dissociation of alkyl radicals and their reverse reactions, the addition of alkyl radicals to olefins were studied by G3MP2 level of theory to obtain a consistent kinetic data set. Both reaction families can be classified depending on the type of radical formed by β bond scission, namely the CH 3 , primary, secondary tertiary radical formed. The kinetics of the reaction classes were described by only a limited number of Arrhenius parameters. The unified A factor of 10 13.7 s -1 was found for all β bond dissociations. The Arrhenius activation energies are 125, 121, 113 and 103 kJ mol -1 , for methyl, primary, secondary, and tertiary radicals, respectively. The activation energies of 32, 25 and 18 kJ mol -1 are calculated for the terminal addition of primary (including methyl), secondary, and tertiary radicals to olefins, respectively. The biologically important nonterminal radical additions to olefins have higher barriers of 37, 31 and 35 kJ mol -1 , respectively. At room temperature both strongly exothermic additions can compete with H-atom abstraction.New groups for Benson's group additivity rules were defined to describe activation parameters for the β bond dissociation reactions. The group values were calculated by using the ab initio heats of formation of transition state structures.

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Activation Energies of Reactions of Methyl Radicals with Organic Molecules¹

Cited by 15 publications

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Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

An updated reaction model for the high-temperature pyrolysis and oxidation of acetaldehyde

Ab initio study on alkyl radical decomposition and alkyl radical addition to olefins

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Activation Energies of Reactions of Methyl Radicals with Organic Molecules1

Cited by 15 publications

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Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

An updated reaction model for the high-temperature pyrolysis and oxidation of acetaldehyde

Ab initio study on alkyl radical decomposition and alkyl radical addition to olefins

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Product

Resources

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Activation Energies of Reactions of Methyl Radicals with Organic Molecules¹