An FTIR study of the Cl‐atom‐initiated reaction of glyoxal

Abstract

AbstractThe kinetics and mechanism of Cl‐atom‐initiated reactions of CHOCHO were studied using the FTIR detection method to monitor the photolysis of Cl2–CHOCHO mixtures in 700 torr of N2–O2 diluent at 298 ± 2 K. The observed product distribution in the [O2] pressure of 0–700 torr combined with relative rate measurements provide evidence that: (1) the primary step is Cl + CHOCHO → HCl + CHOCO with a rate constant of [3.8 ± 0.3(σ)] × 10−11 cm3 molecule−1 s−1; (2) the primary product CHOCO unimolecularly dissociates to CHO and CO with an estimated lifetime of ≤ca. 1 × 10−7 s; (3) alternatively, the CHOCO reacts with O2 leading to the formation of CO, CO2, and most likely the HO radical, but no stable products containing two carbon atoms; (4) the HO2 radical, formed in the secondary reaction CHO + O2 → HO2 + CO, reacts with the CHOCHO with a rate constant ca. 5 × 10−16 cm3 molecule−1 s−1 to form HCOOH and a new transient product resembling that detected previously in the HO2 reaction with HCHO.