Kinetic Studies on the Reactions of Heptafluoropropanes with O(<sup>3</sup>P) and H Atoms at High Temperatures

Yamamoto, O.; Takahashi, Kazuo; Inomata, Tadaaki

doi:10.1021/jp036669k

Cited by 11 publications

(37 citation statements)

References 18 publications

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“…The TST fitted activation energy (9.8 kcal mol À1 ) produced great deviation with the experimental value (15.1 AE 3.3 kcal mol À1 ) from the Arrhenius expression, suggesting that the conventional TST and/or the quantum mechanical tunneling correction based on the Wigner expression used in Ref. [12] to calculate the rate coefficient are very likely inadequate. In addition, the reaction enthalpy and barrier height of R1 were calculated by Lee et al [13] using ab initio, DFT, and IMOMO theory.…”

Section: Introductionmentioning

confidence: 92%

“…[12] are inadequate, VTST calculation are required. In this paper, dual-level (X//Y) direct dynamics calculations are carried out for the title reactions using the variational transition-state theory with the interpolated single-point energies (VTST-ISPE) approach.…”

Section: Kinetics Calculationsmentioning

confidence: 99%

“…CF 3 CF 2 CF 2 + H 2 (R2) in a temperature range from 1000 to 1180 K by a shock tube technique coupled with atomic resonance absorption spectroscopy (ARAS) and obtained the corresponding rate-temperature expressions (in cm 3 mol À1 s À1 ) of k 1 = 10 À9.15AE0.66 exp[À(63 AE 14) kJ mol À1 /RT] and k 2 = 10 À9.44AE0.32 exp [À(57 AE 7) kJ mol À1 /RT]. To evaluate the validity of the experimental results, Yamamoto et al [12] also calculated the rate coefficients k 1 by using the conventional transition state theory (TST) including the tunneling effect based on the Wigner expression. The TST fitted activation energy (9.8 kcal mol À1 ) produced great deviation with the experimental value (15.1 AE 3.3 kcal mol À1 ) from the Arrhenius expression, suggesting that the conventional TST and/or the quantum mechanical tunneling correction based on the Wigner expression used in Ref.…”

Section: Introductionmentioning

confidence: 96%

“…On the contrary, limited experimental data is available for the reactions CF 3 CHFCF 3 (HFC-227ea) and CF 3 CF 2 CHF 2 (HFC-227ca) with H atom. Yamamoto et al [12] measured the rate constants for the reactions CF 3 CHFCF 3 + H ! CF 3 CFCF 3 + H 2 (R1) and CF 3 CF 2 CHF 2 + H !…”

Section: Introductionmentioning

confidence: 99%

“…and (R2b) were obtained at the G2(MP2) level [12]. Thus, a detailed theoretical investigation to get more accurate rate constants over a wide temperature range is very desirable.…”

Section: Introductionmentioning

confidence: 99%

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Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Wang

Zhao

Zhang

2011

Journal of Fluorine Chemistry

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Section: Introductionmentioning

confidence: 92%

Section: Kinetics Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

“…and (R2b) were obtained at the G2(MP2) level [12]. Thus, a detailed theoretical investigation to get more accurate rate constants over a wide temperature range is very desirable.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Wang

Zhao

Zhang

2011

Journal of Fluorine Chemistry

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DFT and ab initio calculations on two reactions between hydrogen atoms and the fire suppressants 2‐H heptafluoropropane and CF₃Br

et al. 2007

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Reaction enthalpies and barrier heights of the reactions CF3Br+H-->CF3+HBr {reaction (1)} and CF3CHFCF3+H-->CF3CFCF3+H2 {reaction (2)} have been calculated at the near state-of-the-art ab initio level, and also by employing the B3LYP, BH&HLYP, BB1K, MPW1K, MPWB1K and TPSS1KCIS functionals. In addition, the integrated molecular orbital+molecular orbital (IMOMO) method has been used to study reaction (2). The ab initio benchmark values of the reaction enthalpy (298 K) and barrier height (0 K) of reaction (2) are reported for the first time {-(0.7+/-0.7) and 13.3+/-0.5 kcal/mole respectively}. When density functional theory (DFT) results are compared with ab initio benchmarks for both reactions (1) and (2), the MPWB1K functional is found to have the best performance of the six functionals used. The IMOMO method with the RCCSD/aug-cc-pVTZ and/or RCCSD(T)/aug-cc-pVTZ levels, as the high levels of calculation on the model system, gives reaction enthalpies and barrier heights of reaction (2), which agree with ab initio benchmark values to within 1 kcal/mole. Computed key geometrical parameters and imaginary vibrational frequencies of the transition state structures of reactions (1) and (2) obtained at different levels of calculation are compared. The magnitudes of the computed imaginary vibrational frequencies of the transition states of both reactions considered are found to be very sensitive to the levels of calculation used to obtain them. The heat of formation (298 K) of CF3CFCF3 calculated at the near state-of-the-art level has a value of -(318+/-3) kcal/mole.

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Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Mok

Lee

et al. 2012

J Comput Chem

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The minimum energy path (MEP) of the reaction, CF3CHFCF3 + H → transition state (TS) → CF3CFCF3 + H2, has been computed at different ab initio levels and with density functional theory (DFT) using different functionals. The computed B3LYP/6‐31++G**, BH&HLYP/cc‐pVDZ, BMK/6‐31++G**, M05/6‐31+G**, M05‐2X/6‐31+G**, UMP2/6‐31++G**, PUMP2/6‐31++G**//UMP2/6‐31++G**, RCCSD(T)/aug‐cc‐pVDZ//UMP2/6‐31++G**, RCCSD(T)/aug‐cc‐pVTZ(spd,sp)//UMP2//6‐31++G**, RCCSD(T)/CBS//M05/6‐31+G**, and RCCSD(T)/CBS//UMP2/6‐31++G** MEPs, and associated gradients and Hessians, were used in reaction rate coefficient calculations based on the transition state theory (TST). Reaction rate coefficients were computed between 300 and 1500 K at various levels of TST, which include conventional TST, canonical variational TST (CVT) and improved CVT (ICVT), and with different tunneling corrections, namely, Wigner, zero‐curvature, and small‐curvature (SCT). The computed rate coefficients obtained at different ab initio, DFT and TST levels are compared with experimental values available in the 1000–1200 K temperature range. Based on the rate coefficients computed at the ICVT/SCT level, the highest TST level used in this study, the BH&HLYP functional performs best among all the functionals used, while the RCCSD(T)/CBS//MP2/6‐31++G** level is the best among all the ab initio levels used. Comparing computed reaction rate coefficients obtained at different levels of theory shows that, the computed barrier height has the strongest effect on the computed reaction rate coefficients as expected. Variational effects on the computed rate coefficients are found to be negligibly small. Although tunneling effects are relatively small at high temperatures (∼1500 K), SCT corrections are significant at low temperatures (∼300 K), and both barrier heights and the magnitudes of the imaginary frequencies affect SCT corrections. © 2012 Wiley Periodicals, Inc.

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Kinetic Studies on the Reactions of Heptafluoropropanes with O(³P) and H Atoms at High Temperatures

Cited by 11 publications

References 18 publications

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

DFT and ab initio calculations on two reactions between hydrogen atoms and the fire suppressants 2‐H heptafluoropropane and CF₃Br

Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

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Kinetic Studies on the Reactions of Heptafluoropropanes with O(3P) and H Atoms at High Temperatures

Cited by 11 publications

References 18 publications

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

DFT and ab initio calculations on two reactions between hydrogen atoms and the fire suppressants 2‐H heptafluoropropane and CF3Br

Rate coefficients of the CF3CHFCF3 + H → CF3CFCF3 + H2 reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Contact Info

Product

Resources

About

Kinetic Studies on the Reactions of Heptafluoropropanes with O(³P) and H Atoms at High Temperatures

DFT and ab initio calculations on two reactions between hydrogen atoms and the fire suppressants 2‐H heptafluoropropane and CF₃Br

Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths