Absolute rate constant measurements for the reaction of atomic hydrogen with acetone, 2-butanone, propionaldehyde, and butyraldehyde in aqueous solution

Arrhenius parameters for the reaction of hydrogen atoms with acetone, 2-butanone, propionaldehyde, and butyraldehyde in aqueous solution have been directly measured by electron paramagnetic resonance free induction decay (FID) attenuation measurements. For these compounds, absolute scavenging rate constants at 25 °C of (1.97 ± 0.10) × 106, (3.82 ± 0.32) × 107, (8.11 ± 0.47) × 107, and (1.14 ± 0.07) × 108 dm3 mol−1 s−1 with corresponding activation energies of 30.7 ± 1.3 (7.5–52.8 °C), 40.1 ± 0.7 (8.1–74.5 °C), 22.2 ± 0.9 (8.0–39.0 °C) and 23.8 ± 0.8 (5.4–67.7 °C) kJ mol−1 were measured, respectively. Competition kinetic measurements have established that greater than 95% of H atom reaction with 2-butanone is by abstraction.