Kinetics of 1,5-Hydrogen Migration in Alkyl Radical Reaction Class

Ratkiewicz, Artur; Bankiewicz, Barbara

doi:10.1021/jp208432z

Cited by 15 publications

(25 citation statements)

References 41 publications

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“…Moreover, Bell-Evans-Polanyi relationships do not allow pre-exponential factors to be modeled. More advanced models that allow the required kinetic parameters to be estimated are methods based on group additivity (GA), [11,12] reaction class methods [13][14][15] and models that are founded on valence bond theory. [16] Relevant to this work is the study performed by Beare and Coote towards understanding barrier heights for hydrogen abstraction reactions from thiols.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Modeling of Hydrogen Abstractions Involving Sulfur Radicals

2013

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One of the requisites for the development of detailed reaction networks is the availability of accurate kinetic data. Group additivity based models linking the Arrhenius parameters to structural characteristics of the transition state have proven to be a valuable tool to obtain those data. In this work, group additivity values are presented to allow a broad range of CH and SH hydrogen abstraction reactions by S radicals to be modeled. Rate coefficients in the temperature range from 300 to 1500 K are obtained by using the CBS-QB3 method in the high-pressure limit and are corrected for tunneling and anharmonicity of rotation about the transitional bond. A total of 149 reactions are studied. From these reactions, a total of 52 group additivity values and 35 resonance corrections are derived. The general applicability of the group additivity method is demonstrated for a test set containing 25 reactions. At 300 K, rate coefficients are on average reproduced within a factor of 2.8. The mean absolute deviations on the Arrhenius parameters are 2 kJ mol(-1) for the activation energy and 0.38 for log A in which A is the pre-exponential factor.

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Section: Introductionmentioning

confidence: 99%

Kinetic Modeling of Hydrogen Abstractions Involving Sulfur Radicals

2013

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“…The choice has been mainly due to the low number of atoms involved, which allows a considerable reduction of the computational effort and the possibility to use higher level theories. Moreover, this system offers a wide availability of experimental and computational backbiting rate coefficient values to be compared with the computational predictions 12, 30, 3132, 33…”

Section: Introductionmentioning

confidence: 99%

Is Quantum Tunneling Relevant in Free‐Radical Polymerization?

Cuccato

Dossi

Polino

et al. 2012

Macro Reaction Engineering

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Quantum tunneling in hydrogen transfer reactions active in FRP is investigated theoretically. Three systems are examined: polyethylene, polystyrene, and poly(vinyl chloride). Kinetic parameters of backbiting reactions are evaluated adopting quantum chemistry. Tunneling corrections are estimated adopting the one‐dimensional Eckart model, which provides a reasonable accuracy along with a limited computational effort. The relevance of quantum tunneling in the investigated systems is highlighted, with focus on the temperature dependence of the tunneling correction in the typical polymerization conditions of the investigated monomers. Obtained results clearly show that tunneling plays an important role in the kinetics estimation of hydrogen abstractions in FRP.

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“…Such a selection is prompted by both the importance of octane, which is one of the most important constituents of gasoline and a reference component in liquid fuel surrogates; as well as the availability of the experimental data [8] with which to compare the RC-TST results. As shown in [19,21,22], for investigated reaction families, hindered rotations (HR) factors are, due to mutual error cancelation, close or equal to unity. Furthermore, it is expected that the HR contributions are similar for all H-shifts, thus small errors resulting from their neglect are mutually cancelled.…”

Section: Branching Ratiosmentioning

confidence: 83%

“…However, the imaginary frequencies are similar and equal to 1881 and 1923 cm -1 for the 1,6 and 1,7 migrations, respectively. In our previous studies [19,20,22] a CCSD(T)/ cc-pVDZ//BH&HLYP/cc-pVDZ was shown to be a cost effective method for exploring the potential energy surface of the intramolecular hydrogen migration in an alkyl radical. Consequently, this method is also used to obtain the energy along the minimum energy path for the rate calculations discussed below.…”

Section: Rate Constants Of the 1-heptyl → 1-heptyl Reactionmentioning

confidence: 99%

First-principles kinetics of n-octyl radicals

Ratkiewicz

2013

Progress in Reaction Kinetics and Mechanism

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Kinetics of the isomerisation and unimolecular degradation of n-octyl radicals have been studied with the reaction class transition state theory (RC-TST) method. To explore the kinetics of the 1,7-H migration reactions family, the accurate high-pressure limits of the rate constants for the reference reaction of this class (1-heptyl → 1-heptyl) have been calculated. Finally, both the achievements reported in this paper and previous developments are employed to obtain theoretical branching ratios of intramolecular H-transfers and unimolecular degradations of all possible n-octyl radicals; the results are in satisfactory agreement when compared to experiment. The application of the rates obtained to the simulation of a simple reactor is also reported.

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Kinetics of 1,5-Hydrogen Migration in Alkyl Radical Reaction Class

Cited by 15 publications

References 41 publications

Kinetic Modeling of Hydrogen Abstractions Involving Sulfur Radicals

Kinetic Modeling of Hydrogen Abstractions Involving Sulfur Radicals

Is Quantum Tunneling Relevant in Free‐Radical Polymerization?

First-principles kinetics of n-octyl radicals

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