FTIR PRODUCT STUDY OF THE CL-INITIATED OXIDATION OF C2H5CL - REACTIONS OF THE ALKOXY RADICAL CH3CHCLO

The Cl-atom-initiated oxidation Of C2H5Cl has been investigated at 295 K using Fourier transform infrared (FTIR) spectroscopy. The observed products are HCl, CO2, CH3COCl, HCHO, CO, CH3OH, HCOOH, CH3OOH, CH3C(O )OOH, and CH2ClCHO. The yields of HCl and CO2 per C2H5Cl consumed are surprisingly high, (157 +/- 6)% and (53 +/- 5)%, and are constant over the C2H5Cl consumption range of 3-15%. To rationalize these results, we propose a new alkoxy radical decomposition pathway: the CH3CHClO ra dical intramolecularly eliminates HCl to produce the acetyl radical, C H3CO, which subsequently reacts to form CO2 and methyl radical oxidati on products. As part of this work, a relative rate technique was used to measure the reactivity of Cl atoms toward C2H5Cl, CD3CH2Cl, and CH3 COCl. We report k(Cl+C2H5Cl) = (8.7 +/- 1.0) X 10(-12), k(Cl+CD3CH2Cl) = (7.34 +/- 1.0) X 10(-12) and k(Cl+CH3COCl) < 1 X 10(-14) (units of cm3 molecule-1 s-1). The implications of our results are discussed in terms of understanding the atmospheric chemistry of halogenated organi c compounds.