Fourteen water-miscible polar solvents were investigated for the separation from their aqueous solutions by salting-out using sodium chloride (4mol dm-3). The following solvents showed the phase separation: acetone, acetonitrile, 1, 4- dioxane, tetrahydrofuran, 1-propanol, and 2-propanol. The chemical properties of the separated organic solvents were determined by measuring ET(30)(=1.196×105/λ (kJmol 1)) and DII.I(=1.196×105(λII-1-λI-1)(kJ mol-1))values from the spectral change of 2, 6-Biphenyl-4-(2, 4, 6-triphenylpyridinio)phenolate (DTP) and bis(1, 3-propanediolato)vanadium(IV) (VO(acac)2), where λ, λI, and λII denote the absorption maximum wavelengths (nm) of DTP and VO(acac)2. Solvent properties of acetone, acetonitrile, 1, 4-dioxane, and tetrahydrofuran were dramatically altered by the salting- out. Acceptability of the phase-separated solvents increased due to the dissolution of water molecules having large acceptor numbers. The ion-pair complex of tris(1, 10-phenanthroline)iron(II) chloride was easily extracted into the phase-separated acetonitrile by the salting-out. Some metal chelates of 1-(2-pyridylazo)-2-naphthol (Hpan) and 8- quinolinol (Hox), 5, 10, 15, 20-tetraphenylporphyrin (H2tpp), and ionic species (H2ox+, ox-, and H4tpp2+) were also extracted into 1, 4-dioxane. The raised donor and acceptor abilities of the phase-separated solvents allowed application to solvent extraction.
The Japan Society for Analytical Chemistry