Deiodination kinetics of water-soluble radiopaques.
Deiodination of diatrizoic acid, an anionic radiopaque, was found to be catalyzed by Cu(II). Through a detailed study of o-iodobenzoic acid, a model compound, the copper-catalyzed SN1 mechanism was established based on observations of common ion, salt, and pH effects. Meta- and para-iodobenzoic acids were unreactive. Deiodination thus was facilitated by a neighboring carboxylate that attracted copper. Iopamidol, a nonionic radiopaque, also underwent deiodination. At pH 7 or above, the hydroxide-ion substitution predominated. At pH below 7, the reaction is in favor of the copper-catalyzed SN1 mechanism.
D003287:Contrast Media; D003973:Diatrizoate; D004355:Drug Stability; D007455:Iodine; D007463:Iodobenzoates; D007479:Iopamidol; D007483:Iothalamic Acid / Q000031:analogs & derivatives*; D007700:Kinetics; D012995:Solubility; D014867:Water
D003287:Contrast Media; D007463:Iodobenzoates; D014867:Water; D003973:Diatrizoate; D007483:Iothalamic Acid; D007455:Iodine; D007479:Iopamidol