Production of [11C]CH3I by single pass reaction of [11C]CH4 with I2.

We report a single pass gas phase route to [11C]CH3I based on production of I from I2 at elevated temperature. I abstracts H from CH4 to yield CH3, which reacts with I2 to form CH3I. A fiber optic spectrometer was used to measure the I2 vapor concentration. [11C]CH3I yield increased with I2 concentration until excessive amounts of condensed I2 began to trap the 11C. The yield of [11C]CH3I was > 50% from [11C]CH4I; its specific activity was 12,000 Ci/mmole. The synthesis takes only 4 min after 11CH4 production and can be repeated without system cleanup.