Solvent extraction of cesium by substituted crown ethers

摘要

The extraction of alkali metal nitrates by 18-crown-6, 21-crown-7, and 24-crown-8 ethers, bearing cyclohexano, benzo-, t-alkylbenzo, and furano- substituents, in 1,2-dichloroethane has been surveyed. Introduction of a furano substituent onto the macrocyclic ring of 18-crown-6 or 21 crown-7 ethers causes a significant reduction in both extraction efficiency and selectivity. Addition of an additional benzo group to dibenzo-21 -crown-7, to give tribenzo-21 -crown-7, decreases both extraction efficiency and selectivity, whereas addition of one or two additional benzo groups to dibenzo-24-crown-8 increases the extraction efficiency and selectivity for the larger ions Rb+ and Cs(sup +) Detailed equilibrium modeling of the extraction by lipophilic 21 -crown-7 ethers indicates that the addition of t-alkyl substituents onto the benzo groups has only a minor effect on the extraction of cesium nitrate by dibenzo-21 -crown-7 ethers.