Rate coefficients for the reactions of OH radicals with Methylglyoxal and Acetaldehyde

Rate coefficients have been measured for the reaction of OH radicals with methylglyoxal from 260 to 333 K using the discharge flow technique and laser‐induced fluorescence detection of OH. The rate coefficient was found to be (1.32±0.30) × 10 −11 cm 3 molecule −1 s −1 at room temperature, with a distinct negative temperature dependence (E/R of −830 ± 300 K). These are the first measurements of the temperature dependence of this reaction. The reaction of OH with acetaldehyde was also investigated, and a rate coefficient of (1.45 ± 0.25) × 10 −11 cm 3 molecule −1 s −1 was found at room temperature, in accord with recent studies. Experiments in which O 2 was added to the flow showed regeneration of OH following the reaction of CH 3 CO radicals with O 2 . However, chamber experiments at atmospheric pressure using FTIR detection showed no evidence for OH production. FTIR experiments have also been used to investigate the chemistry of the CH 3 COCO radical formed by hydrogen abstraction from methylglyoxal. © 1995 John Wiley & Sons, Inc.