Home > Publications database > Reaction between CH<sub>3</sub>C(O)OOH (peracetic acid) and OH in the gas phase: a combined experimental and theoretical study of the kinetics and mechanism |
Journal Article | FZJ-2020-05390 |
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2020
EGU
Katlenburg-Lindau
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Please use a persistent id in citations: http://hdl.handle.net/2128/27433 doi:10.5194/acp-20-13541-2020
Abstract: Peracetic acid (CH3C(O)OOH) is one of the mostabundant organic peroxides in the atmosphere; yet the kinetics of itsreaction with OH, believed to be the major sink, have only been studied onceexperimentally. In this work we combine a pulsed-laser photolysis kineticstudy of the title reaction with theoretical calculations of the ratecoefficient and mechanism. We demonstrate that the rate coefficient isorders of magnitude lower than previously determined, with an experimentallyderived upper limit of 4×10-14 cm3 molec.−1 s−1. The relatively low rate coefficient is in good agreement withthe theoretical result of 3×10-14 cm3 molec.−1 s−1 at 298 K, increasing to ∼6×10-14 cm3 molec.−1 s−1 in the cold uppertroposphere but with associated uncertainty of a factor of 2. The reactionproceeds mainly via abstraction of the peroxidic hydrogen via a relativelyweakly bonded and short-lived prereaction complex, in which H abstractionoccurs only slowly due to a high barrier and low tunnelling probabilities.Our results imply that the lifetime of CH3C(O)OOH with respect toOH-initiated degradation in the atmosphere is of the order of 1 year (notdays as previously believed) and that its major sink in the free and uppertroposphere is likely to be photolysis, with deposition important in theboundary layer.
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