Solvent Extraction of Radium with Crown Ether Carboxylic Acids
作者:M. K. Beklemishev、Sadik. Elshani、C. M. Wai
DOI:10.1021/ac00092a036
日期:1994.10.15
The capabilities of a series of 11 crown ether carboxylic acids with different hydrocarbon substituents have been evaluated for solvent extraction of radium in aqueous solutions. The extraction of radium proceeds from alkaline media into chloroform solutions of the crown ethers. The extraction requires no specific counteranions and is reversible with respect to pH. Substitution of tert-butyl groups in the benzene rings of sym-dibenzo-16-crown-5-oxyacetic acid increases the lipophilicity of the macrocyclic compound and enhances the extraction efficiency for radium. Radium forms a RaL(2)-type complex with this tert-butyl-substituted crown ether carboxylic acid with a binding constant of (4.2 +/- 0.7) x 10(8).