Quantitative Kinetics of the Reaction between CH₂OO and H₂O₂ in the Atmosphere

Abstract

Criegee intermediates (CIs) are generated from the ozonolysis of unsaturated hydrocarbons in the atmosphere. They have an important role in determining the implications of atmospheric bimolecular reactions with other atmospheric species. The reaction between CH2OO and H2O2 plays a crucial role in understanding how CIs impact the HO x budget in the atmosphere. The reaction mechanism and kinetics are critical to atmospheric modeling, which is a prominent challenge in present-day climate change modeling. This is particularly true for bimolecular reactions that involve complex reaction sequences. Here, we report the mechanism and quantitative kinetics of the CH2OO + H2O2 reaction by using a novel dual-level strategy that contains W3X-L//CCSD­(T)-F12a/cc-pVTZ-F12 for the transition state theory and M11-L/MG3S functional method for direct dynamics calculations using canonical variational transition state theory with small-curvature tunneling to obtain both recrossing effects and tunneling. The present work shows that the CH2OO + H2O2 reaction has a negative temperature dependency with the decrease in the rate constant of CH2OO + H2O2 from 1.31 × 10–13 cm3 molecule–1 s–1 to 3.80 × 10–14 cm3 molecule–1 s–1 between 200 and 350 K. The calculated results also show that the CH2OO + H2O2 reaction can have an impact on the H2O2 profile under certain atmospheric conditions. The present findings should have implications for the quantitative kinetics of Criegee intermediates with other hydroperoxides.

Quantitative kinetics for the atmospheric reactions of Criegee intermediates with acetonitrile

“…This also shows that DF-CCSD(T)-F12b/jun-cc-pVDZ can obtain quantitative geometrical parameters and zero-point vibrational energies, which was found in our previous investigations. 39,68,69 Therefore, DF-CCSD(T)-F12b/jun-cc-pVDZ is used to investigate the anti-CH 3 CHOO/syn-CH 3 CHOO + CH 3 CN reactions.…”

Rapid Atmospheric Reactions between Criegee Intermediates and Hypochlorous Acid

“…Previous investigations have shown that W3X-L//CCSD­(T)-F12a/cc-pVTZ-F12 , method can obtain quantitative enthalpies of activation at 0 K for the reactions involving Criegee intermediates. − Therefore, W3X-L//CCSD­(T)-F12a/cc-pVTZ-F12 was used to calculate reaction between the simplest Criegee intermediate (CH 2 OO) and hypochlorous acid (HOCl). Specifically, CCSD­(T)-F12a/cc-pVTZ-F12 , was used to do geometrical optimizations and frequency calculations.…”

Master Equation Studies of the Unimolecular Decay of Thermalized Methacrolein Oxide: The Impact of Atmospheric Conditions

“…Among the important kinetic pathways followed by Criegee intermediates under thermal conditions are: conformational dynamics (involving rotation about one or more carbon–carbon or carbon–oxygen bond within the molecule), hydrogen transfer reactions (which can lead to the formation of OH radicals via hydroperoxide formation), ring-closing reactions (leading to the formation of dioxirane structures), and alternative ring-closing mechanisms (leading to formation of dioxole structures). , Many of the dioxole and dioxirane structures are believed to undergo further unimolecular decay. With respect to the ozonolysis of isoprene, the majority of the experimental and theoretical studies have focused on the properties and reactivity of MVK ,− ,− and formaldehyde oxides, ,− with MACR oxide being relatively less studied. ,− ,− At the same time, it is clear that MACR oxide can play an important role in the ozone-derived chemistry of isoprene: as described by others, and discussed below, anti-MACR oxide is unusually long-lived (τ ≈ 0.10 s at 298 K) with respect to unimolecular decay, ,, making this Criegee intermediate a potentially potent contributor to bimolecular chemistry in the atmosphere.…”