Rate coefficients for the hydrogen abstraction reactions of the ethylene, fluoroethylene, cis- and trans-isomers of the 1,2-difluoroethylene and 1,1-difluoroethylene with the OH radical were computed using TST coupled with G3B3 theory between 200 and 400 K. IRC calculations were performed to confirm the existence of all the transition states. The rate coefficients for the reactions (five test molecules + OH radical) were computed to be k1 = (1.03 ± 0.42) × 10-13 exp[-(1400 ± 114)/T], k2 = (2.46 ± 1.76) × 10-14 exp[-(1956 ± 198)/T], k3 = (4.09 ± 3.6) × 10-15 exp[-(2447 ± 250)/T], k4 = (1.39 ± 0.91) × 10-17 exp[-(1720 ± 180)/T] and k5 = (1.78 ± 0.11) × 10-17 exp[-(1993 ± 176)/T] cm3 molecule-1 s-1 respectively. The atmospheric lifetimes of these compounds due to the hydrogen abstraction reactions are computed to be 48.2, 1502.8, 5.3 × 104, 7.1 × 105 and 1.5 × 106 years, respectively. © 2011 Elsevier B.V. All rights reserved.

Balla Rajakumar

Department Of Chemistry

B. Upendra

ABSTRACTION REACTIONS

ATMOSPHERIC LIFETIME

FLUOROETHYLENE

HYDROGEN ABSTRACTION REACTION

OH radical

Rate coefficients

Temperature range

TEST MOLECULES

TRANS-ISOMERS

Transition state

Ethylene

Free radicals

Hydrogen

Isomers

Abstracting

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IIT Madras

Chemical Physics Letters

The kinetics of the reaction between pinonaldehyde (C 10H16O2) and Cl atom were studied using high level ab initio G3(MP2) and DFT based MPWB1K/6-31 + G(d) and MPW1K/6-31 + G(d) levels of theories coupled with Conventional Transition State Theory in the temperature range between 200 and 400 K. The negative temperature dependent rate expression for the title reaction obtained with Wigner’s and Eckart’s symmetrical tunneling corrections are k(T) =(5.1 ± 0.56) × 10 −19T2.35exp[(2098 ± 2)/T] cm 3 molecule −1s−1, and k(T) =(0.92 ± 0.18) × 10 −19T2.60exp[(2204 ± 4)/T] cm 3 molecule −1 s −1, respectively, at G3(MP2)//MPWB1K method. The H abstraction reaction from the –CHO group was found to be the most dominant reaction channel among all the possible reaction pathways and its corresponding rate coefficient at 300 K is k(Eckart’s unsymmetrical) = 3.86 ×10−10 cm 3 molecule −1 s −1. Whereas the channel with immediate lower activation energy is the H-abstraction from –CH- group (Tertiary H-abstraction site, C g). The rate coefficient for this channel is k Cg(Eckart’s unsymmetrical) = 1.83 ×10−15 cm 3 molecule −1 s −1 which is smaller than the dominant channel by five orders of magnitude. The atmospherically relevant parameters such as lifetimes were computed in this investigation of its reaction with Cl atom. [Figure not available: see fulltext.] © 2016, Indian Academy of Sciences.

Fulltext

Journal of Chemical Sciences

Rate coefficients for hydrogen abstraction reaction of pinonaldehyde (C10H16O2) with Cl atoms between 200 and 400 K: A DFT study

Rate coefficients for the reaction of the hydroxyl radical with CH 3OCH 2F (HFE-161) were computed using transition state theory coupled with ab initio methods, viz., MP2, G3MP2, and G3B3 theories in the temperature range of 200-400 K. Structures of the reactants and transition states (TSs) were optimized at MP2(FULL) and B3LYP level of theories with 6-31G* and 6-311++G** basis sets. The potential energy surface was scanned at both the level of theories. Five different TSs were identified for each rotamer. Calculations of Intrinsic reaction coordinates were performed to confirm the existence of all the TSs. The kinetic parameters due to all different TSs are reported in this article. The rate coefficients for the title reaction were computed to be k = (9 ± 1.08) × - 10 -13 exp [-(1,713 ± 33)/T] cm 3 molecule -1 s -1 at MP2, k = (7.36 ± 0.42) × - 10 -13 exp [-(198 ± 16)/T] cm 3 molecule -1 s -1 at G3MP2 and k = (5.36 ± 1.57) × - 10 -13 exp [-(412 ± 81)/T] cm 3 molecule -1 s -1 at G3B3 theories. The atmospheric lifetimes of CH 3OCH 2F at MP2, G3MP2, and G3B3 level of theories were estimated to be 20, 0.1, and 0.3 years, respectively. © 2011 Wiley Periodicals, Inc.

International Journal of Quantum Chemistry

Kinetic parameters for the reaction of hydroxyl radical with CH 3OCH 2F (HFE-161) in the temperature range of 200-400 K: Transition state theory and Ab initio calculations

The rate coefficients of the CHF2CHFCHF2 (HFC-245ea) + OH reaction were computed using G3B3 theory in the temperature range 200 and 400 K. Geometries were optimized for all reactants, transition states, and products at the B3LYP level of theory using 6-31G* and 6-311++G* basis sets. Three rotamers (R1, R2, and R3) of CHF2CHFCHF2 were identified using a potential energy surface scan. Thirteen independent transition states were identified and confirmed by intrinsic reaction coordinate calculations. The kinetic parameters due to all different transition states are presented in this paper. All the three rotamers were taken into account in computing the rate coefficients. Throughout the temperature range of this study, rotamer R3 contributes significantly (more than 90%), whereas the other two rotamers R1 and R2 contribute less to the total rate coefficient. The rate coefficients for the title reaction were computed to be k = (1.86 ± 0.17) × 10-13 exp[-(748±26)/T] cm3molecule -1s-1 and (1.25 ± 0.23) × 10-13 exp[-(587±50)/T] cm3molecule-1 s-1 with Wigner's and Eckart's unsymmetrical tunneling methods, respectively, and they are in reasonable agreement with the experimentally measured ones. © 2011 Wiley Periodicals, Inc.

International Journal of Chemical Kinetics

Computational study on OH radical reaction with CHF2CHFCHF 2(HFC-245ea) between 200 and 400 K

The rate coefficients of hydroxyl radical (OH) reaction with CF3CHFCH2F (HFC-245eb) were computed using G3MP2 and G3B3 theories between 200 and 400 K. Nine different transition states were identified for the title reaction and confirmed by intrinsic reaction coordinate (IRC) calculations. The contributions of all the individual hydrogen atoms in different rotamers for the title reaction were computed and compared with the results obtained by experimental methods and structure activity relationships (SAR). The rate coefficients for the title reaction were computed to be k = (1.57 ± 0.14) × 10-13 exp[-(690 ± 26)/T] cm3 molecule-1 s-1at G3MP2, and k = (0.97 ± 0.13) × 10-13 exp[-(513 ± 39)/T] cm3 molecule-1 s-1 at G3B3 theories. Theoretically calculated rate coefficients are found to be in good agreement with the experimental results. The tropospheric lifetime of CF3CHFCH2F because of its reaction with OH radicals are computed to be 2.52 and 2.14 years at G3MP2 and G3B3 level of theories, respectively. © 2010 Elsevier B.V. All rights reserved.

Journal of Molecular Structure: THEOCHEM

Kinetics of OH radical reaction with CF3CHFCH2F (HFC-245eb) between 200 and 400 K: G3MP2, G3B3 and transition state theory calculations

Physical Chemistry Chemical Physics

Rate coefficients of H-atom abstraction from ethers and isomerization of alkoxyalkylperoxy radicals

The Journal of Physical Chemistry A

Rate Coefficients for the Reactions of OH with CF3CH2CH3(HFC-263fb), CF3CHFCH2F (HFC-245eb), and CHF2CHFCHF2(HFC-245ea) between 238 and 375 K†

Kinetic parameters of abstraction reactions of OH radical with ethylene, fluoroethylene, cis- and trans-1,2-difluoroethylene and 1,1-difluoroethylene, in the temperature range of 200-400 K: Gaussian-3/B3LYP theory

Journal	Chemical Physics Letters
ISSN	00092614
Open Access	No