Synthesis of [11C]- and (13C)-cyanogen bromide

A fast simple route to the synthesis of [11C]- and (13C)-cyanogen bromide has been developed. Hydrogen [11C]cyanide was produced on-line from [11C]carbon dioxide and reacted with bromide in triethylenglycol dimethyl ether to give a 70-80% decay-corrected radiochemical yield of [11C]cyanogen bromide in 9-11 min, counted from the end of the bombardment. In a typical run, starting from 20.5 GBq (550 mCi) [11C]carbon dioxide, 10.1 GBq (274 mCi) [11C]cyanogen bromide were obtained. The [11C]cyanogen bromide was transferred to a reaction vessel in a stream of nitrogen gas and used in the synthesis of phenyl [11C]cyanate (1a), 4-nitrophenyl [11C]cyanate (1b), 2,4-dinitrophenyl [11C]cyanate (1c), diethyl[11C]cyanamide (2a), phenyl[11C]cyanamide (2b), diphenyl [11C]-cyanamide (2c), 1-([11C]cyano)-4-(dimethylamino)pyridninium bromide (2d), and benzyl [11C]thiocyanate (3a). Compounds 1-3 were obtained with radiochemical yields of 54-98% in 13-27 min counted from [11C]cyanogen bromide. Phenyl [11C]thiocyanate (3b), was obtained in a 12% radiochemical yield. Using the procedure for benzyl [11C]thiocyanate (3a), benzyl (13C)thiocyanate was obtained in 71% yield. (au)