CATALYTIC EFFECT OF COPPER(II) CHLORIDE ON THE RADIOIODINATION OF L-P-IODOPHENYLALANINE

The various iodophenylalanine isomers have teen used for pancreatic im aging studies. In this work a convenient method was developed for inco rporating radioactive iodine onto L-p-iodophenylalanine (p-IPA) using copper(II) chloride to promote radioiodination. Radioiodination condit ions were optimized in terms of reaction time, temperature, copper(II) chloride and p-IPA concentration. Catalytic effect of other metal sal ts such as MgCl2 . 6H(2)O, Ni(NO3). 6H(2)O, also pivalic acid and acet amide as a molten solvent were tested. Radioiodination of p-IPA with ( NaI)-I-131 in organic media such as dimethyl sulfoxide(DMSO), dimethyl formamide(DMF) and Dioxane were achieved and a comparison was made as to the labelling rates. The rate order was found to be as follows: Di oxane > DMSO > DMF The results showed that copper(II) chloride was eff ective for facilitating the exchange reaction with maximum yield (simi lar to 87%) after 60 min at 150 degrees C. Activation energy of 13.3 k cal/mol was also determined.