Temperature‐Dependence of the Rates of Reaction of Trifluoroacetic Acid with Criegee Intermediates

Abstract

The rate coefficients for gas‐phase reaction of trifluoroacetic acid (TFA) with two Criegee intermediates, formaldehyde oxide and acetone oxide, decrease with increasing temperature in the range 240–340 K. The rate coefficients k(CH2OO + CF3COOH)=(3.4±0.3)×10−10 cm3 s−1 and k((CH3)2COO + CF3COOH)=(6.1±0.2)×10−10 cm3 s−1 at 294 K exceed estimates for collision‐limited values, suggesting rate enhancement by capture mechanisms because of the large permanent dipole moments of the two reactants. The observed temperature dependence is attributed to competitive stabilization of a pre‐reactive complex. Fits to a model incorporating this complex formation give k [cm3 s−1]=(3.8±2.6)×10−18 T2 exp((1620±180)/T) + 2.5×10−10 and k [cm3 s−1]=(4.9±4.1)×10−18 T2 exp((1620±230)/T) + 5.2×10−10 for the CH2OO + CF3COOH and (CH3)2COO + CF3COOH reactions, respectively. The consequences are explored for removal of TFA from the atmosphere by reaction with biogenic Criegee intermediates.

Criegee intermediates and their impacts on the troposphere

“…Welz et al 49 Chhantyal-Pun et al 74 Berndt et al 70 Welz et al 49 Welz et al 49 Chhantyal-Pun et al 74 CH2OO + CF3COOH CH2OO + CClF2COOH CH2OO + CF3CF2COOH CH2OO + Pyruvic acid (CH3)2COO + CF3COOH (CH3)2COO + CClF2COOH (CH3)2COO + CF3CF2COOH (CH3)2COO + Pyruvic acid (3.4 ± 0.3) × 10 -10 ξ (3.34 ± 0.16)×10 -10 ξ (4.48 ± 0.23)×10 -10 ξ (0.2 ± 0.02)×10 -10 ξ (3.4 ± 0.3) × 10 -10 ξ (3.9 ± 0.2) × 10 -10 ξ (4.4 ± 0.2) × 10 -10 ξ (0.9 ± 0.1) × 10 Chhantyal-Pun et al 75 Chhantyal-Pun et al 74 Chhantyal-Pun et al 74 Chhantyal-Pun et al 74 Chhantyal-Pun et al 75 Chhantyal-Pun et al 74 Chhantyal-Pun et al 74 Chhantyal-Pun et al 74 CH2OO + NO CH2OO + NO < 6.0 × 10 -14 ξ < 2.0 × 10 -13ϒ…”

“…Further study has shown that the oxidation of SO2 by sCIs can rival the OH oxidation pathway in heavily polluted urban environments, 42 accounting for as much as 33-46% of H2SO4 production at ground level. 99 Recent direct kinetic studies of the reaction of Criegee intermediates with organic acids have identified rate coefficients that are substantially higher, [73][74][75]100 than previous estimates based on theoretical calculations and/or end-product analysis (see 75,104 shows that loss of acids by sCI exceeds 60% of their total loss in South America, South…”

“…The estimated annual average CF3COOH loss contribution by sCI simulated by the STOCHEM-CRI model (Adapted from Chhantyal-Pun et al75 ) …”

Interactive effects of changing stratospheric ozone and climate on tropospheric composition and air quality, and the consequences for human and ecosystem health

“…193 This modelling highlights the variability in transport globally from these sources. However, the limited emission inventory, uncertainties in the chemical degradation pathway, 194 and very limited hazard assessment restricts the usefulness of these results in a global assessment. Because the HFCs that can break down in the atmosphere to produce TFA have long half-lives (1-100 years), 195 they can be distributed globally before significant degradation occurs.…”

Zwitterions for Organic/Perovskite Solar Cells, Light‐Emitting Devices, and Lithium Ion Batteries: Recent Progress and Perspectives

“…[12][13][14] Recently, a significant attention has been paid to the use of zwitterions owing to their solubility in polar solvents for solution processing, [15][16][17] and dipole formation for the transfer of carriers [18][19][20] and ions. [12][13][14] Recently, a significant attention has been paid to the use of zwitterions owing to their solubility in polar solvents for solution processing, [15][16][17] and dipole formation for the transfer of carriers [18][19][20] and ions.…”