Dataset Information

Theoretical Prediction of Activation Free Energies of Various Hydride Self-Exchange Reactions in Acetonitrile at 298 K.

ABSTRACT: Hydride transfer reactions are very important chemical reactions in organic chemistry. It has been a chemist's dream to predict the rate constants of hydride transfer reactions by only using the physical parameters of the reactants. To realize this dream, we have developed a kinetic equation (Zhu equation) in our previous papers to predict the activation free energies of various chemical reactions using the activation free energies of the corresponding self-exchange reactions and the related bond dissociation energies or redox potentials of the reactants. Because the activation free energy of the hydride self-exchange reaction is difficult to measure using the experimental method, in this study, the activation free energies of 159 hydride self-exchange reactions in acetonitrile at 298 K were systematically computed using an accurately benchmarked density functional theory method with a precision of 1.1 kcal mol^-1. The results show that the range of the activation free energies of the 159 hydride self-exchange reactions is from 16.1 to 46.6 kcal mol^-1. The activation free energies of 25?122 hydride transfer reactions in acetonitrile at 298 K can be estimated using the activation free energies of the 159 hydride self-exchange reactions and the corresponding heterolytic bond dissociation free energies of the reactants. The effects of the heteroatom, substituent, and aromaticity on the activation free energies of hydride self-exchange reactions were examined. The results show that heteroatoms, substituents at the reaction center, and the aromaticity of reactants, all have remarkable effects on the activation free energy of hydride self-exchange reactions. All kinetic information provided in this work on the hydride self-exchange reactions in acetonitrile at 298 K should be very useful in chemical labs and chemical industry.

SUBMITTER: Li Y

PROVIDER: S-EPMC6641257 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Theoretical Prediction of Activation Free Energies of Various Hydride Self-Exchange Reactions in Acetonitrile at 298 K.

Li Yang Y Zhu Xiao-Qing XQ

ACS omega 20180124 1

Hydride transfer reactions are very important chemical reactions in organic chemistry. It has been a chemist's dream to predict the rate constants of hydride transfer reactions by only using the physical parameters of the reactants. To realize this dream, we have developed a kinetic equation (Zhu equation) in our previous papers to predict the activation free energies of various chemical reactions using the activation free energies of the corresponding self-exchange reactions and the related bon ...[more]

PMID: 31457934

Similar Datasets

Project description:Many of the radical-molecule reactions are nonelementary reactions with negative activation energies, which usually proceed through two steps. They exist extensively in the atmospheric chemistry and hydrocarbon fuel combustion, so they are extensively studied both theoretically and experimentally. At the same time, various models, such as a two transition state model, a steady-state model, an equilibrium-state model, and a direct elementary dynamics model are proposed to get the kinetic parameters for the overall reaction. In this paper, a conversion temperature T C1 is defined as the temperature at which the standard molar Gibbs free energy change of the formation of the reaction complex is equal to zero, and it is found that when T ? T C1, the direct elementary dynamics model with an inclusion of the tunneling correction of the second step reaction is applicable to calculate the overall reaction rate constants for this kind of reaction system. The reaction class of hydroxyl radical addition to alkenes is chosen as the objects of this study, five reactions are chosen as the representative for the reaction class, and their single-point energies are calculated using the method of CCSD(T)/CBS, and it is shown that the highest conversion temperature for the five reactions is 139.89 K, far below the usual initial low-temperature (550 K) oxidation chemistry of hydrocarbon fuels; therefore, the steady-state approximation method is applicable. All geometry optimizations are performed at the BH&HLYP/6-311+G(d,p) level, and the result shows that the geometric parameters in the reaction centers are conserved; hence, the isodesmic reaction method is applicable to this reaction class. To validate the accuracy of this scheme, a comparison of electronic energy difference at the BH&HLYP/6-311+G(d,p) level and the corrected electronic energy difference with the electronic energy difference at the CCSD(T)/CBS level is performed for the five representative reactions, and it is shown that the maximum absolute deviation of electronic energy difference can be reduced from 2.54 kcal·mol-1 before correction to 0.58 kcal·mol-1 after correction, indicating that the isodesmic reaction method is applicable for the accurate calculation of the kinetic parameters for large-size molecular systems with a negative activation energy reaction. The overall rate constants for 44 reactions of the reaction class of hydroxyl radical addition to alkenes are calculated using the transition-state theory in combination with the isodesmic correction scheme, and high-pressure limit rate rules for the reaction class are developed. In addition, the thermodynamic parameter is calculated and the results indicate that our dynamics model is applicable for our studied reaction class. A chemical kinetic modeling and sensitivity analysis using the calculated kinetic data is performed for the combustion of ethene, and the results indicate the studied reaction is important for the low-to-medium temperature combustion modeling of ethene.

Dataset Information

Theoretical Prediction of Activation Free Energies of Various Hydride Self-Exchange Reactions in Acetonitrile at 298 K.

Publications

Theoretical Prediction of Activation Free Energies of Various Hydride Self-Exchange Reactions in Acetonitrile at 298 K.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets