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 separ ation from their aqueous solutions by salting-out using sodium chlorid e (4 mol dm-3). The following solvents showed the phase separation: ac etone, acetonitrile, 1,4-dioxane, tetrahydrofuran, 1-propanol, and 2-p ropanol. The chemical properties of the separated organic solvents wer e 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 chang e of 2,6-diphenyl4-(2,4,6-triphenylpyridinio)phenolate (DTP) and bis(1 ,3-propanediolato)vanadium(IV) (VO(acac)2), where lambda, lambda(I), a nd lambda(II) denote the absorption maximum wavelengths (nm) of DTP an d VO(acaC)2. Solvent properties of acetone, acetonitrile, 1,4-dioxane, and tetrahydrofuran were dramatically altered by the salting-out. Acc eptability of the phase-separated solvents increased due to the dissol ution of water molecules having large acceptor numbers. The ion-pair c omplex of tris(1,10-phenanthroline)iron(II) chloride was easily extrac ted into the phase-separated acetonitrile by the salting-out. Some met al chelates of 1-(2-pyridylazo)-2-naphthol (Hpan) and 8-quinolinol (Ho x), 5,10,15,20-tetraphenylporphyrin (H2tpp), and ionic species (H2ox+, ox-, and H4tPP2+) were also extracted into 1,4-dioxane. The raised do nor and acceptor abilities of the phase-separated solvents allowed app lication to solvent extraction.