Primary vs. secondary H-atom abstraction in the Cl-atom reaction with n-pentane

Pandit, Shubhrangshu; Hornung, B.; Dunning, Greg T.; Preston, Thomas J.; Brazener, Kristian; Orr-Ewing, Andrew J.

doi:10.1039/c6cp07164c

Cited by 10 publications

(8 citation statements)

References 64 publications

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“…Fitted distributions of HCl scattering angles, summed over all vibrational and rotational quantum states, are plotted in Figure for the three collision energies. At the higher collision energies, most products are forward scattered, although a broad distribution is characteristic of facile abstraction of an H-atom from an sp 3 -hybridized carbon atom. ,,,,− However, the scattering angle distributions becomes increasingly isotropic at lower collision energies, supporting the findings reported in section of the growing importance of long-lived intermediates, and possible steering of Cl-atom approach directions by long-range attractive forces. The plots in Figure indicate that these complexes survive for time scales of 10 4 –10 5 fs, which exceed the rotational period of the energized chloropropyl radicals.…”

Section: Resultssupporting

confidence: 68%

“…These oxygen-containing polar organic compounds contribute to the formation of secondary organic aerosols. However, the mechanisms of reactions of alkenes with chlorine atoms are less studied than those of alkanes, which involve direct hydrogen abstraction pathways to produce alkyl radicals. − The reactions of Cl atoms with unsaturated VOCs typically exhibit greater mechanistic complexity, with competition between addition and abstraction reactions leading to different outcomes. − Building on our group’s prior experimental and computational studies of the dynamics of prototypical Cl-atom reactions with alkenes, , the current work explores the factors influencing this competition in the first steps of the Cl-atom initiated chain of atmospheric oxidation reactions of unsaturated VOCs.…”

Section: Introductionmentioning

confidence: 99%

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Collision Energy Dependence of the Competing Mechanisms of Reaction of Chlorine Atoms with Propene

et al. 2019

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Quasi-classical trajectory simulations examine the reaction of Cl with propene across a range of collision energies, from 7 to 28 kJ mol -1 . The majority (70% at 7 kJ mol -1 , 86% at 14 kJ mol -1 and 93% at 28 kJ mol -1 ) of reactive trajectories produce HCl by direct abstraction of a hydrogen atom from the methyl group of propene, but the remainder involve a variety of delayed mechanisms. Among these longer-lived trajectories, transient formation of an energized 1-chloropropyl radical intermediate is predominant, with only a minor contribution from the 2-chloropropyl radical and roaming pathways. The branching ratios between these intermediate states are largely invariant to collision energy, although the overall proportion of indirect trajectories increases at lower collision energies. The greater role for longer-lived trajectories is reflected in the computed product scattering angle distributions, which become more isotropic at lower energies. However, the distributions of population over vibrational and rotational states of the product HCl do not change with collision energy because they are controlled by the dynamics late along the reaction path.

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Section: Resultssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Collision Energy Dependence of the Competing Mechanisms of Reaction of Chlorine Atoms with Propene

et al. 2019

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“…This post-six-atom age of accurate full-dimensional PES-based reaction dynamics has just recently started with the investigations of the O + C 2 H 4 , OH + CH 4 , H/F/Cl/OH + CH 3 OH, − F/Cl/O/OH + C 2 H 6 , − OH – + CH 3 I, and F – (H 2 O) + CH 3 I reactions. Furthermore, using empirical valence bond PESs the dynamics of the Cl + C 3 H 6 /C 5 H 12 reactions was also investigated. , Besides the bimolecular reactions, we should also note the pioneering work of Bowman and co-workers on CH 3 CHO photodissociation and their recent advances on efficient PES developments for many-atom systems such as CH 3 NHCOCH 3 ( N -methylacetamide) and NH 2 CH 2 COOH (glycine) . These first-principles studies have three key steps.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, using empirical valence bond PESs the dynamics of the Cl + C 3 H 6 /C 5 H 12 reactions was also investigated. 43,44 Besides the bimolecular reactions, we should also note the pioneering work of Bowman and co-workers on CH 3 CHO photodissociation 45 and their recent advances on efficient PES developments for many-atom systems such as CH 3 NHCOCH 3 (N-methylacetamide) and NH 2 CH 2 COOH (glycine). 46 These first-principles studies have three key steps.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Reaction Dynamics beyond Six-Atom Systems

et al. 2021

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Moving beyond the six-atomic benchmark systems, we discuss the new age and future of first-principles reaction dynamics, which investigates complex, multichannel chemical reactions. We describe the methodology starting from the benchmark ab initio characterization of the stationary points, followed by full-dimensional potential energy surface (PES) developments and reaction dynamics computations. We highlight our composite ab initio approach providing benchmark stationary-point properties with subchemical accuracy, the Robosurfer program system enabling automatic PES development, and applications for the Cl + C 2 H 6 , F + C 2 H 6 , and OH – + CH 3 I post-six-atom reactions focusing on ab initio issues and their solutions as well as showing the excellent agreement between theory and experiment.

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“…Cl atoms play an important role in the troposphere and stratosphere, especially in destroying the stratospheric ozone layer . In the marine boundary layer, the concentrations of tropospheric Cl atoms were about 10 4 molecules cm –3 and even reached ∼1 × 10 6 molecules cm –3 . − Many studies have found that Cl atoms play an important role in the gas-phase degradation of volatile organic compounds (VOCs), oxygen-containing VOCs (OVOCs), and intermediate VOCs. − The rate constants could be 1–2 orders of magnitude higher than the OH radicals. − Due to the atmospheric photochemistry “activated” by the Cl atom, it can directly affect the formation of secondary inorganic and organic aerosols and lead to the formation of ozone (O 3 ). − …”

Section: Introductionmentioning

confidence: 99%

Impact of the Water Molecule on the Gas-Phase Reaction between Acetone and Cl Atoms

Fan

Wang

Shi

et al. 2021

ACS Earth Space Chem.

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The role of the water molecule in the atmospheric reaction between CH3COCH3 and Cl atoms was investigated at the theoretical level of CCSD(T)/aug-cc-pVTZ//BHandHLYP/aug-cc-pVDZ. The reaction between acetone and Cl atoms proceeds through three paths: an H-abstraction reaction, a −CH3 abstraction reaction, and an addition/elimination reaction by Cl, leading to the formation of CH3COCH2 + HCl (+H2O), CH3CO + CH3Cl (+H2O), and CH3COCl + CH3 (+H2O), respectively. The formation pathway of CH3COCH2 + HCl in the three paths occupies a dominant position, with a rate constant of 1.08 × 10–12 cm3 molecule–1 s–1. However, water-assisted CH3COCH3 + Cl reactions become more complex, proceeding through 10 different paths. At 298 K, the effective rate constant for CH3COCH2 + HCl + H2O formation is 8.46 × 10–15 cm3 molecule–1 s–1, and the effective rate constant decreases by 3–4 orders of magnitudes in the temperature range of 216.69–298.15 K. Therefore, it is concluded that water exerts a hindering effect on the CH3COCH3 + Cl + H2O reaction under atmospheric conditions, but it is not enough to change the dominant position of the CH3COCH3 + Cl reaction under anhydrous conditions.

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Primary vs. secondary H-atom abstraction in the Cl-atom reaction with n-pentane

Cited by 10 publications

References 64 publications

Collision Energy Dependence of the Competing Mechanisms of Reaction of Chlorine Atoms with Propene

Collision Energy Dependence of the Competing Mechanisms of Reaction of Chlorine Atoms with Propene

First-Principles Reaction Dynamics beyond Six-Atom Systems

Impact of the Water Molecule on the Gas-Phase Reaction between Acetone and Cl Atoms

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