Constantes d'association de quelques éthers de polyéthyléne glycols avec Na+, K+, Cs+et Tl+

Abstract

We report data concerning the association of monovalent cations with some polyethyleneglycol ethers that we have prepared.1:1 association constants K_A have been obtained in methyl alcohol at 25 °C using selective glass electrode potentiometric measurements for Na⁺ and K⁺ and conductimetric measure ments for Cs⁺ and Tl⁺.The values obtained for K_A and for the selectivity ratio K_A(K⁺)/K_A(Na⁺) increase with the number of coordinating sites.Replacement of the two methoxy terminal groups in the chain by primary amide or ester groups reduces the complexing properties of the ligand.The stereochemistry of the coordination is discussed in the case of some biphenylic polyethers.