THE MERCURY PHOTOSENSITIZED HYDROGENATION OF PROPYLENE AND THE ACTIVATION ENERGY OF THE REACTION C3H7+H2 = C3H8+H

Abstract

The reactions initiated in hydrogen–propylene mixtures by Hg(³P₁) atoms were studied over the temperature range from room temperature to 320 °C. At 260° and above, the rate of formation of propane and the rate of pressure decrease are linear functions of the hydrogen pressure. This effect is attributed to the reaction C₃H₇+H₂ = C₃H₈+H and its activation energy is estimated to be equal to or slightly greater than 12.5 kcal. per mole. This is 1.2 kcal. per mole greater than the corrected value for the activation energy of the analogous reaction C₂H₅+H₂ = C₂H₆+H. The ratio k_combination/k_{dispropotionation} is estimated to be approximately 2.0 at room temperature in the case of isopropyl radicals.