SYNTHESIS OF 3,5-DIISOPROPYL[CARBOXY-C-14]SALICYCLIC ACID AND ITS CU-67 COMPLEX

The synthesis of 3,5-diisopropyl[carboxy-C-14]salicylic acid was achieved via Kolbe-Schmitt carboxylation of potassium 2,4-diisopropylphenolate. The yield of this acid was 81% based upon the weight of the product and 93% based upon radioactivity incorporated into the labeled acid which contains 98% C-14 in the carboxyl group (specific activity = 5.1-mu-Ci/mg). The labeled acid was characterized by ultraviolet spectrophotometry and purity established by thin-layer chromatography, autoradiography, and liquid scintillation counting. A 90% yield of the double labeled C-14, Cu-67-complex (specific activity = 4.6-mu-Ci Cu-67/mg) was obtained using conditions developed with non-radioactive reactants. The presence of Cu-67 in this complex was established using gamma-ray emission spectrophometry.