Formation of CH₃I in a NaI and methyl alkyl ketone solution under gamma irradiation conditions

We investigated the effects of concentrations of NaI and methyl alkyl ketone on the formation of methyl iodide under gamma irradiation conditions. Without irradiation, the formation of methyl iodide does not occur. For the formation of methyl iodide, the solution pH should be brought to lower than 6 by radiolytic decomposition of ketones and air. At a pH below 6, the iodide was oxidized into iodine, allowing for the formation of CH₃I from the reaction of iodine and the CH₃ radical. When the concentrations of NaI and methyl alkyl ketone were similar, the concentration of methyl iodide was generally at its highest, and as the gamma dose increased, the concentration of methyl iodide increased. (author)