Ring-size and substituent effects in the solvent extraction of alkali metal nitrates by crown ethers in 1,2-dichloroethane and 1-octanol

The extraction of alkali metal nitrate salts by solutions of crown ethers in each of the two diluents 1,2-dichlorethane and l-octanol has been surveyed. The crown ethers include 18-crown-6, 21-crown-7, and 24-crown-8 ethers bearing cyclohexano, benzo, t-alkylbenzo, and/or furano substitutents. The extraction efficiencies of the different crown ethers are examined in terms of ring-size, substituent, and solvent effects. Partition ratios for the crown ethers between water and either 1,2-dichloroethane or l-octanol are discussed. The extraction selectivities, expressed as the separation factor for cesium over sodium, are examined in relation to crown ether structure.