Solvent Effects on Cesium Complexation with Crown Ethers from Liquid to Supercritical Fluids.

Wai, C. M.

Technical Information Center Oak Ridge Tennessee

关键词: Solvents;    Crown ethers;    Cesium complexes;    Chloroform;    Nuclear magnetic resonance;   

RP-ID  :  DE2004822406

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Nuclear magnetic resonance (NMR) techniques were used to study crown ether-water interactions in solvents of low dielectric constants such as chloroform and carbon tetrachloride. Water forms a 1:1 complex with a number of crown ethers including 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18=crown-6, dicyclohexano-24-crown 8, and dibenzl-24-crown-8 in chloroform. Among these crown ethers, the 18-crown-6-H2 complex has the largest equilibrium constant (K=545) and 97% of the crown is complexed to water in chloroform. Addition of carbon tetrachloride to chloroform lowers the equilibrium constants of the crown-water complexes. The partition coefficients of crown ethers (D=crown in water/crown in solvent) between water and organic solvent also vary with solvent composition.