Rate constant measurements for the reaction Cl + CH2O .fwdarw. HCl + CHO. Implications regarding the removal of stratospheric chlorine

Abstract

The flash photolysis resonance fluorescence technique was employed to investigate the rate constant for the reaction Cl + CH20 -»• HCI + CHO from 223 to 323 K. An Arrhenius fit of the data gives ki = (1.09 ± 0.40) X 10"10 exp[-(131 ± 98)/T] in units of cm3 molecule'1 s'1. The results are compared to two very recent kinetic studies and are assessed in view of the reaction's role in disrupting the Cl-CIO stratospheric ozone depletion chain.

Determination of the mechanism of the oxidation of the trichloromethyl radical by the photolysis of chloral in the presence of oxygen

“…(23) C1+ CH20 -+ HC1+ HCO k23 = 4.22 X 10IOM-' sec-l at 296 K [9] Reaction (5) is one of the chain-propagating reactions, and in reaction (22) Hz works as radical trapping, since H combines 0 2 rapidly to form HOz in our experimental conditions, and HO2 does not work as a chain carrier.…”

Rate coefficients and production of vibrationally excited HCl from the reactions of chlorine atoms with methanol, ethanol, acetaldehyde and formaldehyde

“…Despite increasing recognition of the importance of formaldehyde in both stratospheric and marine boundary layer chemistry, there have been no direct measurements of the rate coefficient for reaction (3) since 1981. The two most comprehensive studies 14,15 reported good agreement at room temperature, but disagreed about the temperature dependence of the rate coefficient. At lower stratospheric temperatures of $220 K, the two expressions differ by 25%.…”

“…The room temperature kinetic measurements are all in good agreement but there is some uncertainty as to the temperature dependence of reaction (3). 14,15 The reaction of chlorine atoms with acetaldehyde…”

Photoelectron Spectroscopy and Structures of X−⋅⋅⋅CH2O (X=F, Cl, Br, I) Complexes

“…The reactions between halogens and CH 2 O have attracted attention as the hydrogen abstraction reaction of Br+CH 2 O is an important termination step in the Br‐dominated destruction of ozone in the Arctic troposphere, as well as being a major sink for CH 2 O in this area [15,16] . Kinetics and mechanisms have been reported for F, Cl, Br, and I atom reactions [17–22] . MP2 calculations have estimated the barrier heights of the hydrogen abstraction reactions to be in the region of 4.4 kJ mol −1 to 17.2 kJ mol −1 for the F, Cl, and Br reactions.…”