An ab Initio Study of the Kinetics of the Reactions of Halomethanes with the Hydroxyl Radical. 1:  CH2Br2

Louis, Florent; González, Carlos; Huie, Robert E.; Kurylo, Michael J.

doi:10.1021/jp001182m

Cited by 2 publications

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“…Other previous computational work shows larger deviations at low temperatures and have errors across the temperature range. Louis, et al 17 , performed calculations at the PM4(SDTQ) level with two large basis sets and found they overpredicted the rate constant between 250 and 400 K. They too treated the rotation about the C-H-OH axis as a hindered rotor, but used the Wigner tunneling correction. Their barrier heights are between 3.5 and 3.7 kcal/mol, so they are in good agreement with experiment, like our results.…”

Section: Verified By Comparison To Experiments By Paul Blowers and Kyle Hollingsheadmentioning

confidence: 99%

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Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Blowers

Hollingshead

2009

J. Phys. Chem. A

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In this work, the global warming potential (GWP) of methylene fluoride (CH(2)F(2)), or HFC-32, is estimated through computational chemistry methods. We find our computational chemistry approach reproduces well all phenomena important for predicting global warming potentials. Geometries predicted using the B3LYP/6-311g** method were in good agreement with experiment, although some other computational methods performed slightly better. Frequencies needed for both partition function calculations in transition-state theory and infrared intensities needed for radiative forcing estimates agreed well with experiment compared to other computational methods. A modified CBS-RAD method used to obtain energies led to superior results to all other previous heat of reaction estimates and most barrier height calculations when the B3LYP/6-311g** optimized geometry was used as the base structure. Use of the small-curvature tunneling correction and a hindered rotor treatment where appropriate led to accurate reaction rate constants and radiative forcing estimates without requiring any experimental data. Atmospheric lifetimes from theory at 277 K were indistinguishable from experimental results, as were the final global warming potentials compared to experiment. This is the first time entirely computational methods have been applied to estimate a global warming potential for a chemical, and we have found the approach to be robust, inexpensive, and accurate compared to prior experimental results. This methodology was subsequently used to estimate GWPs for three additional species [methane (CH(4)); fluoromethane (CH(3)F), or HFC-41; and fluoroform (CHF(3)), or HFC-23], where estimations also compare favorably to experimental values.

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Section: Verified By Comparison To Experiments By Paul Blowers and Kyle Hollingsheadmentioning

confidence: 99%

“…CBS-RAD/B3LYP/6-31*), a ref18 (G2/MP2/6-31g*), b ref17 (PMP4(SDTQ)/6-311G(3df,2p), c ref17 (PMP4(SDTZ)/6-311++g(2df,2pd)), d ref12 (QCISD(T)/6-311++G(2df,p)//QCISD/6-311g(d,p)[QCISD/6-31g(d)]///PM3, e ref12 (CCSD(T)//MP2/cc-pVTZ///PM3), f ref27 …”

mentioning

confidence: 99%

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Blowers

Hollingshead

2009

J. Phys. Chem. A

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“…11 In addition, several authors have developed correlations between the kinetic parameters of those OH radical reactions and the molecular parameters of HFCs. 12,13 From a theoretical point of view, several HFCs have been studied, mainly fluoromethanes and fluoroethanes [14][15][16][17][18][19][20][21][22][23][24][25] and, very recently, fluoropropanes. 26 These studies can be classified as those based on the conventional transition-state theory (TST) and, on the other hand, the studies based on the generalized transition state theory.…”

Section: Introductionmentioning

confidence: 99%

Canonical Variational Transition-State Theory Study of the CF₃CH₂CH₃ + OH Reaction

González‐Lafont¹,

Lluch²,

Varela‐Álvarez³

et al. 2007

J. Phys. Chem. B

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Variational transition-state theory rate constants with multidimensional tunneling contributions using the small curvature method have been calculated for the CF3CH2CH3 (HFC-263fb) + OH reaction over a temperature range from 200 to 373 K. The mPW1B95-41.0 hybrid functional, parametrized by Albu and Swaminathan to generate theoretical rate constants nearly identical to the experimental values for the CH3F + OH reaction, has been used in conjunction with the 6-31+G** basis set to explore the potential energy surface of the title reaction. The good agreement found between theoretical predictions and the experimental data available suggests that the present approach is an excellent option to obtain high-quality results at low computational cost for direct dynamics studies of hydrogen abstraction reactions from complex hydrofluorocarbons. The reliability of the structure activity relationship used to estimate rate constant values for OH reactions with hydrofluorocarbons is also discussed in detail.

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An ab Initio Study of the Kinetics of the Reactions of Halomethanes with the Hydroxyl Radical. 1: CH₂Br₂

Cited by 2 publications

References 0 publications

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Canonical Variational Transition-State Theory Study of the CF₃CH₂CH₃ + OH Reaction

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An ab Initio Study of the Kinetics of the Reactions of Halomethanes with the Hydroxyl Radical. 1: CH2Br2

Cited by 2 publications

References 0 publications

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH2F2 and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH2F2 and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Canonical Variational Transition-State Theory Study of the CF3CH2CH3 + OH Reaction

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An ab Initio Study of the Kinetics of the Reactions of Halomethanes with the Hydroxyl Radical. 1: CH₂Br₂

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Estimations of Global Warming Potentials from Computational Chemistry Calculations for CH₂F₂ and Other Fluorinated Methyl Species Verified by Comparison to Experiment

Canonical Variational Transition-State Theory Study of the CF₃CH₂CH₃ + OH Reaction