Complex formation of crown ethers with cations in water-organic solvent mixtures: Part X. Thermodynamics of interactions between Na+ ion and 15-crown-5 ether in acetone-water mixtures at 298.15Â K

The thermodynamic functions of complex formation of 15-crown-5 ether (15C5) with sodium cation (Na+) in the mixtures of water with acetone at 298.15 K have been calculated. The equilibrium constants of complex formation of 15C5 with Na+ have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by the calorimetric method. The complexes are enthalpy-stabilized but entropy-destabilized in acetone-water mixtures. The effects of hydrophobic hydration, preferential solvation of 15C5 by a molecule of organic solvent and solvation of Na+ on the complex formation processes have been discussed.