Ion-pair extraction of alkali metal nitrate salts by lipophilic, benzo-substituted 24-crown-8 ethers

The extraction of alkali metal nitrate salts by 24-crown-8 ethers bearing multiple benzo substituents has been surveyed in 1,2-dichloroethane diluent at 25 degrees C. The results reveal that the addition of benzo-substituents onto the 24-crown-8 increases both the extraction efficiency and the selectivity for the larger cations. Substitution of branched alkyl groups onto the benzo rings of 24-crown-8 ethers has a relatively small influence on their extraction properties.