Supercritical fluid synthesis inthe preparation of β+-emitting labelled compounds

A system for synthesis in supercritical fluids has been developed for the microscale synthesis of pharmaceuticals labelled with 11C. Supercritical ammonia was selected as the reaction medium and the following variables were studied in detail: trapping efficiency, cell design, substrate concentration, operation design, and temperature and pressure conditions. Alkylation of phenol by [11C]methyl iodide to yield [methyl-11C]anisole was used as a model reaction for evaluation of the system. The results show an increased radiochemical yield in the highly compressible near-critical region. (au) (40 refs.)