Synthesis of [11C]iodomethane by iodination of [11C]methane

[11C]iodomethane was synthesized by iodination of [11C]methane with iodine. The reaction was carried out in a system where [11C]methane, helium and iodine vapours were mixed and heated. The formed [11C]iodomethane was continuously removed from the reaction mixture and the unchanged [11C]methane was recirculated into the reaction chamber by a pump. The decay-corrected radiochemical yield was 83% after a production time of 7 min (from trapped [11C]methane). The specific radioactivity was better than 550 GBq/μmol (15 Ci/mmol) at the end of the synthesis.