Kinetics of the hydrogen abstraction ROH + H → RO^• + H₂ reaction class

Abstract

This paper presents an application of the reaction class transition state theory (RC-TST) to predict thermal rate constants for the hydrogen abstraction R OH + H → R O • + H 2 reaction class, where R is an alkyl group. We have derived all parameters for the RC-TST method for this reaction class from rate constants of 19 representative reactions, coupling with linear energy relationships (LERs) and the barrier height grouping (BHG) approach. 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 method has less than 25% systematic errors in the predicted rate constants, whereas the RC-TST/BHG method has less than 35% error when compared to explicit rate calculations.

Kinetics of α hydrogen abstractions from thiols, sulfides and thiocarbonyl compounds

“…Therefore, inclusion of the tunneling corrections in the DGAV o s would lead to temperature dependent DGAV o s. A group additivity model hence benefits from separating tunneling contributions from the calculated Arrhenius parameters. Alternatively, tunneling can be modeled explicitly using correlations with other known properties of the reaction as exemplified in the reaction class transition state theory of Truong et al 30,32,33 In the reaction class transition state theory, tunneling corrections for hydrogen abstractions are modeled by inclusion of a temperature dependent tunneling factor, which is taken as the ratio of the tunneling coefficients for a target reaction and the reference reaction. 30 In this work, the Eckart method is used to determine the tunneling contributions.…”

“…[22][23][24][25][26][27][28][29][30][31][32][33] Sumathi et al 27,28 proposed a method to obtain accurate kinetic data for hydrogen abstraction reactions using supergroups that encompass the reactive moiety of the transition state structure. The major advantage of these supergroups is that they can account for non-atom-centered contributions, i.e.…”

“…Truong et al 29 used reaction class transition state theory to predict rate coefficients for hydrogen abstraction reactions between methyl and alkanes 30 and between hydrogen and alcohols. 32,33 In this approach the rate coefficient of a target reaction can be calculated by multiplying the rate coefficient of a reference reaction with a set of four correction factors accounting for effects of symmetry, tunneling, partition function and potential energy. In this work, the group additivity (GA) method as proposed by Saeys et al 25 and further extended by Sabbe et al 26 is used to model the kinetics of hydrogen abstractions involving organosulfur compounds.…”

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

“…The reaction class transition state theory (RC-TST) has demonstrated to be a powerful method for filling the gap. It has been successfully applied to more than 10 reaction classes [17][18][19][20][21][22][23]. The RC-TST method provides an effective way to extrapolate accurate rate constants from a small number of representative reactions to the whole reaction class.…”

“…• + H 2 [23]. In this study, to obtain a complete picture of the kinetics of initial stadium of alcohols combustion, we applied the RC-TST method to derive all parameters for estimating the rate constants of any reaction belonging to the R-OH + H → R…”