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 hav e been directly measured by electron paramagnetic resonance free induc tion decay (FID) attenuation measurements. For these compounds, absolu te scavenging rate constants at 25 degrees C of (1.97 +/- 0.10) x 10(6 ), (3.82 +/- 0.32) x 10(7) (8.11 +/- 0.47) x 10(7), and (1.14 +/- 0.07 ) x 10(8) dm(3) mol(-1) s(-1), with corresponding activation energies of 30.7 +/- 1.3 (7.5-52.8 degrees C), 40.1 +/- 0.7 (8.1-74.5 degrees C ), 22.2 +/- 0.9 (8.0-39.0 degrees C) and 23.8 +/- 0.8 (5.4-67.7 degree s C) kJ mol(-1) were measured, respectively. Competition kinetic measu rements have established that greater than 95% of .H atom reaction wit h 2-butanone is by abstraction.