Abstract. Peracetic acid (CH3C(O)OOH) is one of the most
abundant organic peroxides in the atmosphere; yet the kinetics of its
reaction with OH, believed to be the major sink, have only been studied once
experimentally. In this work we combine a pulsed-laser photolysis kinetic
study of the title reaction with theoretical calculations of the rate
coefficient and mechanism. We demonstrate that the rate coefficient is
orders of magnitude lower than previously determined, with an experimentally
derived upper limit of 4×10-14 cm3 molec.−1 s−1. The relatively low rate coefficient is in good agreement with
the 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 upper
troposphere but with associated uncertainty of a factor of 2. The reaction
proceeds mainly via abstraction of the peroxidic hydrogen via a relatively
weakly bonded and short-lived prereaction complex, in which H abstraction
occurs only slowly due to a high barrier and low tunnelling probabilities.
Our results imply that the lifetime of CH3C(O)OOH with respect to
OH-initiated degradation in the atmosphere is of the order of 1 year (not
days as previously believed) and that its major sink in the free and upper
troposphere is likely to be photolysis, with deposition important in the
boundary layer.
Rate coefficient and mechanism of the OH-Initiated degradation of cyclobutanol: A combined experimental and theoretical study
