Evaluation of the reaction parameters and thermodynamics of the iodide-exchange preparation of radioiodinated 15-(p-iodophenyl) pentadecanoic acid by both solid phase and solution methods

Abstract

Two isotopic exchange procedures are described for the labelling of 15‐(p‐iodophenyl) pentadecanoic acid with radioiodine in the presence of ammonium sulphate and cuprous chloride as catalysts. The methods afforded regioselective and high specific activity products with radiochemical yields of 92% and 85% within relatively short reaction times. High pressure liquid chromatographic separation resulted in high radiochemically pure product suitable for medical application. Kinetic studies revealed second order iodine–iodine exchange reactions with an activation energy of 13.7 Kcal/mole for the solid state radioiodination with ammonium sulphate and 15.3 Kcal/mole for the copper catalyzed exchange reaction. © 1998 John Wiley & Sons, Ltd.