CHEMICAL-PROPERTIES OF WATER-MISCIBLE SOLVENTS SEPARATED BY SALTING-OUT AND THEIR APPLICATION TO SOLVENT-EXTRACTION

Fourteen water-miscible polar solvents were investigated for the separation from their aqueous solutions by salting-out using sodium chloride (4 mol 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 E(T)(30) (=1.196 X 10(5)/lambda (kJ mol-1)) and D(II.I) (=1.196 X 10(5) (kJ mol-1)) values from the spectral change of 2,6-diphenyl4-(2,4,6-triphenylpyridinio)phenolate (DTP) and bis(1,3-propanediolato)vanadium(IV) (VO(acac)2), where lambda, lambda(I), and lambda(II) 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.