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 eth ers in each of the two diluents 1,2-dichlorethane and l-octanol has be en surveyed. The crown ethers include 18-crown-6, 21-crown-7, and 24-c rown-8 ethers bearing cyclohexano, benzo, t-alkylbenzo, and/or furano substitutents. The extraction efficiencies of the different crown ethe rs are examined in terms of ring-size, substituent, and solvent effect s. Partition ratios for the crown ethers between water and either 1,2- dichloroethane or l-octanol are discussed. The extraction selectivitie s, expressed as the separation factor for cesium over sodium, are exam ined in relation to crown ether structure.