Kinetics of D Atom Reactions with H2, CH4, and D2CO

The activation energies and steric factors of the abstraction reactions D+D2CO→D2+DCO and D+CH4→HD+CH3 have been determined by the technique of competing reactions. Mixtures of formaldehyde-d2 and H2 as well as formaldehyde-d2 and methane were photolyzed over a temperature interval in the region of 350°. Measurements of the HD/D2 product ratios as a function of temperature, initial compositions, and light intensity, give the activation energies and steric factors for D+D2CO→D2+DCO, the values E=4.8±0.6 kcal, P=0.04, and for D+CH4→HD+CH3, the values E=7.8±0.6 kcal, P=0.025. These are based on the values E=5.4 kcal and P=0.11 for the reaction D+H2→HD+H.