Reactions of Methane with Iodine Activated by Radiative Neutron Capture. II

Further experiments have been conducted to clarify the mechanism of the unique reaction whereby I128 freshly formed by the I127(n,γ)I128 process is able to replace hydrogen in methane (I128+CH4→CH3I+H). They show that the yield of CH3I128 is decreased by the presence of the inert gases He, A, and Xe but not to the extent which would be the case if the activation energy for the reaction were supplied solely by kinetic energy of the I128. I2, CH3I, C2H5I, C3H7I and NO, which have lower ionization potentials than that of the I atom are all more effective than the inert gases in reducing the yield. The organic yield of I128 is higher when alkyl iodides are used as the source of iodine than when I2 is used. The ability of the freshly formed I128 to react with C2H6 or C6H6 is much less than with CH4. Reactions of I2 with CH4 sensitized by argon and xenon occur when several hundred mm of the inert gas is present during exposures to 105r or more of gamma radiation.