.gamma. Radiolysis of ethanol vapor

Bansal, K. M.; Freeman, Gordon R.

doi:10.1021/ja01028a001

Cited by 14 publications

(9 citation statements)

References 4 publications

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“…Unfortunately, there is not much experimental data available to compare with the calculated differences in the reactivity of primary C-H bonds as the b groups are varied. In the case of ethanol, the methylene group is more reactive [19][20][21] than methyl; in formates, the formyl hydrogen is more reactive 22 than methyl; in aldehydes, ketones and acetates, the acetyl hydrogen is more reactive than methyl; in unsaturated hydrocarbons, addition 23 across the multiple bond is faster than abstraction etc. Consequently, the experimentally observed dominant channel rate constant is not of much use in establishing the validity of the calculated non-next neighbor effects in this reaction family.…”

Section: Introductionmentioning

confidence: 99%

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Sumathi

Green

2003

Phys. Chem. Chem. Phys.

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Ab initio molecular orbital theory calculations are performed at the complete basis set (CBS-Q) level to determine thermochemical parameters (D f H 298 , S 298 , C T p ) of alcohols, methyl ethers, formates, acetates, hydroperoxides, methyl alkylperoxides and the corresponding methoxy, primary and secondary alkoxy radicals derived from these molecular families. A consistent set of 12 Benson groups transferable among these six molecular families is derived from CBS-Q results via regression together with 20 hydrogen bond increment (HBI) group values for estimating the thermochemistry of oxymethyl ( CH 2 OX), oxyethyl (CH 3 CH OX), oxyisopropyl ((CH 3 ) 2 C OX) with varying substituent X ( ¼ H, CH 3 , C(O)H, C(O)CH 3 , OH, OCH 3 ) and alkoxycarbonyl (ROC(O) ) radicals. These new groups are useful in estimating the thermochemistry of large oxygenated molecules and radicals involved in complex chemical reaction mechanisms. The kinetics of nearly 50 elementary bimolecular hydrogen abstraction reactions belonging to eight different reaction families viz.,are studied using transition state theory coupled with CBS-Q energetics. The calculated barrier height within a given reaction family varies with the nature of the b substituents. The reliability of the calculated variations in the barrier height with varying b substituents is determined through comparison of the calculated rate constants with the scarcely available experimental data. Thermodynamically consistent generic rate rules have been derived in terms of group additivity. New transferable supergroup values corresponding to the thermochemistry of the reactive moiety in transition structures are developed. The effect of non-next neighbor substituents on the enthalpy of the supergroup is quantified using Evans-Polanyi relations.

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Section: Introductionmentioning

confidence: 99%

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Sumathi

Green

2003

Phys. Chem. Chem. Phys.

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“…The potential energy surface was calculated at a rather accurate G2M (rcc, MP2) level of theory, based on the B3LYP/6-311+G(d,p) geometries. The calculated rate constants are valid over a wide range of temperatures from 300 to 3000 K and showed excellent agreement with available experimental data [38]. Thus, for the RC-TST application here, we used these calculated rate constants, which can be fitted to the Arrhenius equation as [7] k r1 (T ) = 2.…”

Section: Rate Constantsmentioning

confidence: 55%

Kinetics of the hydrogen abstraction R−OH + H → R^• −OH + H₂ reaction class: An application of the reaction class transition state theory

Ratkiewicz

Bieniewska

Truong

2010

Int. J. Chem. Kinet.

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This paper presents an application of the reaction class transition state theory (RC-TST) to predict thermal rate constants for hydrogen abstraction reactions of the type R-OH + H → R • -OH + H 2 . We have derived all parameters for the RC-TST method with linear energy relationships (LERs) and the barrier height grouping (BHG) approach for this reaction class from rate constants of 37 representative reactions divided in two types of hydrogen abstraction, namely from α carbon sites and non-α carbon sites two training sets. Error analyses indicate that the RC-TST/LER, where only reaction energy is needed, and RC-TST/ BHG, where no other information is needed, can predict rate constants for any reaction in this reaction class with satisfactory accuracy for combustion modeling. Specifically for this reaction class, the RC-TST/LER and RC-TST/BHG methods have, respectively, less than 40% and 90% systematic errors in the predicted rate constants, when compared to the explicit full TST/Eckart method. The branching ratio analysis shows that in the low-temperature regime α abstractions are dominant, whereas, for

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“…In total, 195 direct rate coefficient measurements in 16 data sets within a range of T = 840–1899 K were collected for the C 2 H 5 OH decomposition channels (R176, R177); theoretical calculations of Sivaramakrishnan et al and Park et al were also considered. One measured rate coefficient at 423 K was included for C 2 H 5 OH + CH 3 = CH 3 CHOH + CH 4 , as well as theoretical calculations for all three product channels of C 2 H 5 OH + CH 3 (R187–R189). For the reaction C 2 H 4 + OH = C 2 H 3 + H 2 O (R104), 22 data points in two data sets were utilized ( T = 651–1746 K), together with theoretical determinations from various authors .…”

Section: Rate Parameters To Be Optimized Their Prior Uncertainty Dommentioning

confidence: 99%

Development of an Ethanol Combustion Mechanism Based on a Hierarchical Optimization Approach

Olm

Varga

Valkó

et al. 2016

Int. J. Chem. Kinet.

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A detailed multi-purpose reaction mechanism for ethanol combustion was developed for the use in high-fidelity numerical simulations describing ignition, flame propagation and species concentration profiles with high accuracy. Justified by prior analysis, an optimization of 44 Arrhenius parameters of 14 crucial elementary reactions using several thousand direct and indirect measurement data points was performed, starting from the ethanol combustion mechanism of Saxena and Williams (2007). The final optimized mechanism was compared to 13 reaction mechanisms frequently used in ethanol combustion with respect to their accuracy in reproducing the various types of experimental data.

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.gamma. Radiolysis of ethanol vapor

Cited by 14 publications

References 4 publications

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Kinetics of the hydrogen abstraction R−OH + H → R^• −OH + H₂ reaction class: An application of the reaction class transition state theory

Development of an Ethanol Combustion Mechanism Based on a Hierarchical Optimization Approach

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.gamma. Radiolysis of ethanol vapor

Cited by 14 publications

References 4 publications

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Oxygenate, oxyalkyl and alkoxycarbonyl thermochemistry and rates for hydrogen abstraction from oxygenates

Kinetics of the hydrogen abstraction R−OH + H → R• −OH + H2 reaction class: An application of the reaction class transition state theory

Development of an Ethanol Combustion Mechanism Based on a Hierarchical Optimization Approach

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Kinetics of the hydrogen abstraction R−OH + H → R^• −OH + H₂ reaction class: An application of the reaction class transition state theory