Ab initio direct dynamics studies on the hydrogen abstraction reactions of CF2H2 and CF3H with F atom

Wang, Li; Liu, Jing-Yao; Li, Ze-Sheng

doi:10.1016/j.chemphys.2008.04.011

Cited by 4 publications

(2 citation statements)

References 24 publications

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“…Figure compares the current results with the prior literature for F + fluoromethanes, including both experimental − and theoretical results. ,− As discussed in section , a two-transition-state model was used for the reactions between F and fluoromethanes, which involved the barrierless formation of a submerged van der Waals complex prior to the first-order saddle point for H abstraction. A more rigorous treatment of the outer transition state would be beneficial but is beyond the scope of the present work.…”

Section: Resultsmentioning

confidence: 77%

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

2023

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A new detailed chemical kinetic mechanism is presented for small fluorinated hydrocarbons. Ab initio electronic structure theory is used to provide heats of formation with subchemical accuracy. The ANL0 method is extended to include fluorine. The resulting heats of formation at 0 K are in excellent agreement with 36 benchmark species in the Active Thermochemical Tables, with a mean error of μ = −0.02 kJ/mol and a standard deviation of σ = 0.91 kJ/mol. The thermophysical properties for 92 small-molecule H/C/O/F species are computed. The rate coefficients for 40+ H-abstraction reactions involving H, O, F, OH, OF, HO2, and various methyl radicals with CH4, CH3F, CH2F2, CHF3, CH2O, and CHFO are discussed. The computed rate constants are in excellent agreement with the available literature. Additionally, 30+ rate constants are provided for F abstraction, which are several orders of magnitude smaller than H abstraction. The thermophysical properties and rate constants are provided in a mechanism. This mechanism is the first in a series of theory-based investigations into the thermal destruction of per- and polyfluorinated species.

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Section: Resultsmentioning

confidence: 77%

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

2023

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“…103 We extended this to higher temperatures using an extended Arrhenius expression with n = 1.44; this was the "best" parameterized value based on the trends in this parameter for the other fluoromethanes. For the other fluoromethanes (including methane), there are no measurements for H abstraction by F atoms above about 500 K. There are several quantum chemical calculations reported in the literature for these reactions (see, for instance, Wang et al 104 ). We did not use the functional forms for the rate constants from those works.…”

Section: Ch 2 F 2 + F → Chf 2 + Hfmentioning

confidence: 99%

A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures

Burgess

Babushok

Manion

2021

Int J of Chemical Kinetics

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In this work, we compiled and evaluated rate expressions for reactions relevant to the decomposition and combustion of CH 2 F 2 (difluoromethane, refrigerant R-32) in CH 2 F 2 /O 2 /N 2 flames. The recommended values have been used in premixed flame calculations, reported elsewhere, to model experimentally derived burning velocities determined using a constant volume spherical flame method. In this work, we also provide a detailed description of the reaction pathways for decomposition and combustion of CH 2 F 2 . This work is part of a larger effort at NIST to characterize and predict the flammability of new refrigerant working fluids and their blends for consideration as replacements of current refrigerants with high global warming potentials.

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Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄

Lü

Kuang

et al. 2011

Int J of Quantum Chemistry

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ABSTRACT:The mechanism and dynamics of the H þ CD 4 ! CD 3 þ HD (I) and H þ CH 4 ! CH 3 þ H 2 (II) reactions have been investigated by electronic structure methods. The minimum-energy path and vibrational frequencies along the intrinsic reaction coordinate are calculated at MP2/cc-pVDZ level. Energy distributions of the products are also obtained by the direct classical trajectory calculations at the MP2/ cc-pVDZ level. It is found that most of the available energy appears as product translational energy, and very little of the available energy is partitioned into internal excitation of the HD (H 2 ) product for reaction I (II), which is in agreement with the experimental evidence. The results indicate that the experimental results could be reproduced by the direct MP2 molecular dynamics calculations. The rotational state distributions of the products show the HD (H 2 ) products are formed with lower rotational quantum numbers than the CD 3 (CH 3 ) products.

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Ab initio direct dynamics studies on the hydrogen abstraction reactions of CF2H2 and CF3H with F atom

Cited by 4 publications

References 24 publications

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures

Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄

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Ab initio direct dynamics studies on the hydrogen abstraction reactions of CF2H2 and CF3H with F atom

Cited by 4 publications

References 24 publications

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

A chemical kinetic mechanism for combustion and flame propagation of CH2F2/O2/N2 mixtures

Direct MP2 molecular dynamics studies of H atom reaction with CD4 and CH4

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A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures

Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄