Energy Disposal by Chemical Reactions

Holmes, Bert E.; Setser, D. W.

doi:10.1007/978-1-4684-3557-3_2

Cited by 9 publications

(7 citation statements)

References 323 publications

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“…40 In general, our results confirm that at the TS the CsF bond has been broken to a greater extent than the CsH bond, but these bond orders, see Table 9, are closer together than those of previous studies. 3,14 The HsF bond has been formed to an extent of 0.3 or less, depending on the level of theory. The double CdC bond has formed by about onethird.…”

Section: Resultsmentioning

confidence: 99%

“…As a test case for comparison of DFT and ab initio methods, we selected the 1,2-HF/DF elimination from 1,1,1-trifluoroethane-d 0 ,-d 3 . This unimolecular dehydrohalogenation reaction has been thoroughly studied by thermal and chemical activation methods, 3 and because it contains three fluorines, it is similar to the trifluoroalkanes, trifluoro alcohols, and trifluoroethers we will be investigating and, also it should be a more stringent test of the computational methods than either fluoro-or difluoroethane.…”

Section: Introductionmentioning

confidence: 99%

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Comparisons between Density Functional Theory and Conventional ab Initio Methods for 1,2-Elimination of HF from 1,1,1-Trifluoroethane: Test Case Study for HF Elimination from Fluoroalkanes

2002

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Density functional theory, DFT, and high-level conventional ab initio calculations, together with RRKM calculations, have been employed to study the nature of the transition state geometry for 1,2 elimination of HF from 1,1,1-trifluoroethane-d 0 ,-d 3 ; these serve as test cases for 1,2-HF elimination from fluorocarbons. Quantities calculated include structural parameters, bond indices, energies, atomic charges, vibrational frequencies, and moments of inertia for the reactant and the transition state geometry. The threshold energies for HF and DF elimination were computed and the vibrational frequencies and moments of inertia data were used with the RRKM theory to calculate the entropies of activation, preexponential factors for thermal activation, and also rate constants and the kinetic isotope effect for both thermally and chemically activated 1,1,1-trifluoroethane-d 0 ,-d 3 . Of all the methods employed, the hybrid DFT methods incorporating either the threeparameter exchange functional of Becke with the correlation functional of Perdew and Wang or the correlation functional of Lee, Yang, and Parr were found to give results more consistent with the experimental studies. Both the 6-31G(d′,p′) and cc-PVDZ basis sets gave comparable agreement with experiment and suggest that basis sets of double-quality in the valence region, which include polarization functions, appear to be adequately flexible to describe the systems studied here. There appears to be little to be gained in going from the computationally efficient DFT calculations to the computationally very expensive methods such as G2 or MP2.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparisons between Density Functional Theory and Conventional ab Initio Methods for 1,2-Elimination of HF from 1,1,1-Trifluoroethane: Test Case Study for HF Elimination from Fluoroalkanes

2002

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“…However, the HO-NO and HO-CIO potential surfaces will not be identical and that part of the energy disposal associated with the separation of the products can be quite different. 29…”

Section: Discussionmentioning

confidence: 99%

Studies of hydrogen and oxygen atom reactions by hydroxyl infrared chemiluminescence

Agrawalla¹,

Manocha²,

Setser³

1981

J. Phys. Chem.

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The vibrational energy disposal to OH and relative rate constants have been measured for the O + HI and GeH4 reactions and for the H + N02 and C102 reactions. The experiments were done in a flowing afterglow apparatus which gives arrested vibrational distributions as shown by comparisons of the OH(i>) distribution from + N02 with other data in the literature. The energy disposal pattern for the O atom reactions closely resembles that for F (or Cl) atom reactions. Comparison of the relative emission intensities from + N02 and H + Cl2 and the accepted rate constants for the reactions permits a selection to be made for the better vibrational OH '-* '-\ Einstein coefficients. Emission from NO was observed from the + N02 reaction confirming predictions that NO is involved in the energy disposal.

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“…The surprisal is defined as I ( v ) = −ln[ P ( v )/ P 0 ( v )] and surprisal plots show I ( v ) vs f v = E v /⟨ E av ⟩. Vibrational surprisal plots are usually linear for H atom abstraction reactions, − ( f v ) = λ v 0 + λ v f v ; the slope, λ v , is a global measure of the deviation from the statistical prediction, and the intercept provides estimation for the P v ( v = 0) population. One advantage from observation of HOD is that modeling the 2400–2900 cm –1 spectrum provides an experimental estimation of populations of v 3 = 0 states, which can be used to test the estimates from surprisal analysis.…”

Section: Methods Of Spectra Analysismentioning

confidence: 99%

Branching Ratios and Vibrational Distributions in Water-Forming Reactions of OH and OD Radicals with Methylamines

Butkovskaya

Setser

2016

J. Phys. Chem. A

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Reactions of OH and OD radicals with (CH3)3N, (CH3)2NH, and CH3NH2 were studied by Fourier transform infrared emission spectroscopy (FTIR) of the water product molecules from a fast-flow reactor at 298 K. The rate constants (4.4 ± 0.5) × 10(-11), (5.2 ± 0.8) × 10(-11), and (2.0 ± 0.4) × 10(-11) cm(3) molecule(-1) s(-1) were determined for OD + (CH3)3N, (CH3)2NH, and CH3NH2, respectively, by comparing the HOD emission intensities to the HOD intensity from the OD reaction with H2S. Abstraction from the nitrogen site competes with abstraction from the methyl group, as obtained from an analysis of the HOD and D2O emission intensities from the OD reactions with the deuterated reactants, (CD3)2NH and CD3NH2. After adjustment for the hydrogen-deuterium kinetic isotope effect, the product branching fractions of the hydrogen abstraction from the nitrogen for di- and monomethylamine were found to be 0.34 ± 0.04 and 0.26 ± 0.05, respectively. Vibrational distributions of the H2O, HOD, and D2O molecules are typical for direct hydrogen atom abstraction from polar molecules, even though activation energies are negative because of the formation of pre-transition-state complexes. Comparison is made to the reactions of hydroxyl radicals with ammonia and with other compounds with primary C-H bonds to discuss specific features of disposal of energy to water product.

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Energy Disposal by Chemical Reactions

Cited by 9 publications

References 323 publications

Comparisons between Density Functional Theory and Conventional ab Initio Methods for 1,2-Elimination of HF from 1,1,1-Trifluoroethane: Test Case Study for HF Elimination from Fluoroalkanes

Comparisons between Density Functional Theory and Conventional ab Initio Methods for 1,2-Elimination of HF from 1,1,1-Trifluoroethane: Test Case Study for HF Elimination from Fluoroalkanes

Studies of hydrogen and oxygen atom reactions by hydroxyl infrared chemiluminescence

Branching Ratios and Vibrational Distributions in Water-Forming Reactions of OH and OD Radicals with Methylamines

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