Studies on Synthetic Ionophores. X. Transport Behavior of Na+ and K+ with an ω-Hydroxy Carboxylic Acid Containing Octaether Linkages as a Synthetic Analog of Natural Carboxylic Acid Ionophores through an Organic Liquid Membrane

2-[[2-[2-[2-[2-[2-[2-[2-(2-Hydroxyethoxy)phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]methyl]benzoic acid (1) was employed as a carrier to transport alkali metal ions. The transport selectivity sequence through 1,2-dichloroethane membrane was K+ ≥ Rb+ > Cs+ > Na+ ≥ Li+. The high preference of K+ to Na+ in competitive transport through 1,2-dichloroethane–toluene was consistent with the difference of solubility between the potassium and sodium salts of 1. However, the separate transport rates of K+ and Na+ through 1,2-dichloroethane were comparable. The amount of water incorporated from aqueous to organic layer by the sodium salt was much more than by the potassium salt, and the amounts were dependent on the stirring rates of the two layers. The sodium salt lowered the interfacial tension between the aqueous and organic layers, while the potassium salt did not change it. Emulsion-like aggregates of the sodium salt in the organic layer were observed by dynamic light scattering. The above experiments ...