| Abstrakt: |
Competitive solvent extractions of alkali metal cations from aqueous solutions by the crown ether carboxylic acids sym-dibenzo-13-crown-4-oxyacetic acid, 2; sym-dibenzo-19-crown-6-oxyacetic acid, 3, and sym-dibenzo-14-crown-4-oxyacetic acid, 4, in chloroform have been conducted. Influences of aqueous phase pH and metal ion concentrations upon the concentrations of metals and complexing agent in the organic phase are assessed and compared with those reported for sym-dibenzo-16-crown-5-oxyacetic acid, 1. Extraction selectivity orders of K > Rb > Na ≈ Cs > Li, K > Rb ≥ Na ≈ Cs > Li, and K > Na > Rb > Cs ≈ Li were found for extractions using 2, 3, and 4, respectively. In terms of selectivity and metal extractability, 3 surpasses 1, 2, and 4. |
