Gas-Phase Radiolysis of Isobutane

Abstract

The radiolysis of (CH3)3CD—I2 and (CH3)3CH–(CD3)3CD–I2 mixtures has been investigated as a function of pressure (0.2 to 75 cm) and temperature (30° to 225°C). Propane, which is the major product, is mostly formed by a hydride transfer reaction such as sec−C3H7++(CH3)3CH→C3H8+(CH3)3C+. From the distribution of the isotopic propanes produced in the radiolysis of (CH3)3CD it can be concluded that hydrogen atoms in the sec-propyl ion are randomized in various degrees depending on the pressure of isobutane. Ethane is mainly formed by a hydride transfer reactionC2H5++(CH3)3CH→C2H6+C4H9+.. Two distinct processes lead to the formation of ethylene, (a) molecular elimination from isobutane and (b) reaction of vinyl ions with isobutane. The effect of xenon, krypton, and argon on the product distribution and the randomization of the sec-propyl ion is discussed in some detail.