The Cu(+)-assisted radioiodination Kit: Mechanistic study of unexplored parameters concerning the acidity and redox properties of the reaction medium

Nucleophilic Cu(+)-assisted radioiodination can be optimally performed at pH approximately 2.3 by using conventional reducing agents such as gentisic acid and SnSO(4), mixed or separately. A mechanistic overview of the Cu(+)-radioiodination method is presented in the extended pH-range of 1-4.4. At lower pH, these usual reducing agents show a distinct behaviour. Oxidizing acids (HSO(4)(-), H(3)PO(4)) must be avoided, where as redox neutral acids (trifluoroacetic acid or methanesulfonic acid) or reducing acids (H(2)SO(3), H(3)PO(2)) are well tolerated. The presence of reducing acids makes the use of the usual reducing agents redundant.