Kinetic parameters for the reaction of OH radical with cis-CHFCHCHF2, trans-CHFCHCHF2, CF2CHCHF2 and CF2CCHF: Hybrid meta DFT and CVT/SCT/ISPE calculations

Ramanjaneyulu, C.; Rajakumar, B.

doi:10.1016/j.jfluchem.2015.08.012

Cited by 5 publications

(18 citation statements)

References 39 publications

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“…Research groups of Rajakumar et al − and Zhang et al have recently reported computational results on the reactions of halogenated alkenes with OH radicals. The authors concluded that the reactions predominantly proceed via the addition of OH radical to the C–C double bond rather than direct hydrogen atom abstraction.…”

Section: Resultsmentioning

confidence: 99%

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

et al. 2018

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The rate constants for the reactions of OH radical with ( E)- and ( Z)-isomers of CFCF═CHCl and CHFCF═CHCl have been measured over the temperature range of 250-430 K. Kinetic measurements have been performed using flash and laser photolysis methods combined with laser-induced fluorescence. Arrhenius rate constants have been determined as k(( E)-CFCF═CHCl) = (1.09 ± 0.03) × 10 · exp[(50 ± 10)K/ T], k(( Z)-CFCF═CHCl) = (8.02 ± 0.19) × 10 · exp[-(100 ± 10)K/ T], k(( E)-CHFCF═CHCl) = (1.50 ± 0.03) × 10 · exp[(160 ± 10)K/ T], and k(( Z)-CHFCF═CHCl) = (1.36 ± 0.03) × 10 · exp[(360 ± 10)K/ T] cm molecule s. Infrared absorption spectra have also been measured at room temperature. The atmospheric lifetimes of ( E)-CFCF═CHCl, ( Z)-CFCF═CHCl, ( E)-CHFCF═CHCl, and ( Z)-CHFCF═CHCl have been estimated as 8.9, 20, 4.6, and 2.6 days, respectively, and their global warming potentials and ozone depletion potentials were determined as 0.23, 0.88, 0.060, and 0.016 and 0.00010, 0.00023, 0.000057, and 0.000030, respectively. Additionally, the rate constants for OH radical addition and IR spectra of these compounds were determined computationally. Consistent with experiment, our calculations indicate that the reactivity toward OH radical addition is reduced as ( Z)-CHFCF═CHCl > ( E)-CHFCF═CHCl > ( E)-CFCF═CHCl > ( Z)-CFCF═CHCl, where the ( E)/( Z) reactivity is reversed for CFCF═CHCl and CHFCF═CHCl. The calculations reproduced the observed temperature dependencies of the rate constants for the OH radical reactions, which is slightly positive for ( Z)-CFCF═CHCl but negative for the other compounds.

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Section: Resultsmentioning

confidence: 99%

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

et al. 2018

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“…As described in Section , we performed MP2 and CCSD(T) level single-point energy evaluations after M062X-level geometry optimizations to explore the potential energy surface for the OH addition to CFCl=CFCl and CHF=CHF. The combination of M062X-level geometry optimizations and high-level ab initio single-point energy evaluations has been applied to investigations on the mechanism, kinetics, and thermochemistry of atmospheric reactions of various fluorinated compounds. − Nevertheless, it would be rather difficult to provide distinct discussions on the magnitude of the uncertainties of the theoretical rate constants in the present study and on the origins of the not very large but not negligible differences observed between the experiments and theory. However, the following experimentally observed reactivity trends were consistent with our calculated results.…”

Section: Resultsmentioning

confidence: 99%

Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

et al. 2019

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The rate constants for the OH radical reactions with halogenated ethenes were investigated experimentally and computationally. The rate constants for the reactions of OH radicals with (E)-CFCl=CFCl (k 1 ), (Z)-CFCl=CFCl (k 2 ), and (E)-CHF=CHF (k 3 ) were measured using flash and laser photolysis methods. The temporal profile of the OH radical was monitored by a laser-induced fluorescence technique. Kinetic measurements were carried out over the temperature range of 250−430 K. Arrhenius rate constants were determined to be kThe quoted uncertainties are 95% confidence levels and do not include systematic errors. Infrared absorption spectra were measured at room temperature. The atmospheric lifetimes and the global warming potentials of (E)-CFCl=CFCl, (Z)-CFCl=CFCl, and (E)-CHF=CHF were estimated to be 4.3, 4.2, and 1.2 days and 0.035, 0.036, and 0.0056, respectively. The ozone depletion potentials of (E)-CFCl=CFCl and (Z)-CFCl=CFCl were determined to be 0.00011 and 0.00010, respectively. The photochemical ozone creation potentials of the halogenated ethenes were less than 1/4 that of ethene. In addition, the (E)/(Z) differences in the energy and IR spectra of the CFCl=CFCl and CHF=CHF molecules were computationally examined. The reactivities of these halogenated ethenes toward OH radicals were investigated through the combination of DFT and ab initio computations. The rate constants calculated for the OH radical reactions of these halogenated ethenes showed reasonable agreement with the experimentally determined values. Our computational results for the CFCl=CFCl and CHF=CHF (E)/(Z) isomeric pairs indicated that the rate constants toward OH radicals are larger for the higher-energy geometrical isomers than for the lower-energy counterparts.

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“…Quantum tunneling effects were performed by using the small curvature tunneling (SCT) method. Through the CVT rate constant at temperature T is given by the following relation:

k^{CVT} (T) = \min_{s} k^{GT} (T, s),

where

k^{GT} (T, s) = \frac{σ k_{B} T}{h} \frac{Q^{GT} (T, s)}{ϕ^{R} (T)} e \frac{- v_{MEP (s)}}{k_{B} T} .

Here, min s signifies location of generalized transition state (GTS) at a minimized dividing surface s , k GT ( T , s ) is a GTS theory rate constant at the dividing surface s , r is the symmetry factor to illustrate the possibility of more than one symmetry‐related reaction path, k B is Boltzmann's constant, h is Planck's constant, ϕ R ( T ) is the reactant classical partition function per unit volume, Q GT ( T , s ) is the classical partition function of GTS with a local zero of energy v MEP( s ), and with all rotational symmetry numbers set to unity.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Quantum tunneling effects were performed by using the small curvature tunneling (SCT) method. Through the CVT [29][30][31][32] rate constant at temperature T is given by the following relation:…”

Section: Computational Detailsmentioning

confidence: 99%

ZnO and TiO₂ clusters as catalyst in the addition and abstraction reaction of acrylic acid with the OH radical

Aazaad

Lakshmipathi

2019

Int J of Chemical Kinetics

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The present work displays the theoretical analysis on the role of metal oxide clusters as an effective catalyst in the reaction between acrylic acid and OH radical, which has an energy barrier of 12.4 kcal/mol. The formation of metal oxide cluster such as ZnO and TiO2 with varying size from monomer to hexamer is analyzed using cohesive energy, which increases with cluster size. Adsorption of acrylic acid on clusters reveals that dimer ZnO and tetramer TiO2 are good adsorbed entities. The dimer ZnO and tetramer TiO2 clusters have reduced the barrier height. However, from the thermodynamical analysis of H‐abstraction and OH addition reaction, the dimer ZnO cluster is found to be a good catalyst than a tetramer TiO2 cluster. The favorable H abstraction and OH addition reactions are feasible at the active methylene group (–CH). OH addition reactions dominate over the H abstraction reaction. Further, the presence of metal oxide clusters enhances the rate of the reaction between acrylic acid and OH radical. The kinetics of the favorable reaction with a dimer ZnO cluster has a rate constant of 7.80 × 10−11 cm3 molecule−1 s−1, which is higher than the literature report (1.75 × 10−11 cm3 molecule−1 s−1). Overall, ZnO and TiO2 metal oxide clusters can be effectively utilized as catalyst.

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Kinetic parameters for the reaction of OH radical with cis-CHFCHCHF2, trans-CHFCHCHF2, CF2CHCHF2 and CF2CCHF: Hybrid meta DFT and CVT/SCT/ISPE calculations

Cited by 5 publications

References 39 publications

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

ZnO and TiO₂ clusters as catalyst in the addition and abstraction reaction of acrylic acid with the OH radical

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Kinetic parameters for the reaction of OH radical with cis-CHFCHCHF2, trans-CHFCHCHF2, CF2CHCHF2 and CF2CCHF: Hybrid meta DFT and CVT/SCT/ISPE calculations

Cited by 5 publications

References 39 publications

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF3CF═CHCl and CHF2CF═CHCl

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF3CF═CHCl and CHF2CF═CHCl

Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

ZnO and TiO2 clusters as catalyst in the addition and abstraction reaction of acrylic acid with the OH radical

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Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

ZnO and TiO₂ clusters as catalyst in the addition and abstraction reaction of acrylic acid with the OH radical