| Co-Investigator(Kenkyū-buntansha) |
NISHIMOTO Jun Saga University, Chemistry, Associate Professor, 機器分析センター, 助教授 (80253582)
TAKAMUKU Toshiyuki Saga University, Chemistry, Associate Professor, 理工学部, 助教授 (70291838)
|
|---|
| Research Abstract |
Present study was carried out to explore a new separation method using homogenous mixed organic aqueous solutions, especially to find a new partition phenomenon of analytes into micro solvent clusters that form in mixed solvents. Advantage of this method is to be able to extract highly charge chemical species that can't be extracted into conventional organic solvents such as chloroform, because the organic phases contain about 4 M of water. Furthermore, the micro-solvent clusters are precursor complexes for the phase-separation and chemical species dissolve in the clusters. The followings are summary of this study.
1. Water-soluble lithium porphyrin complex was extracted into acetonitrile phases by addition of NaCl or Na_2SO_4. The charge of extracted-chemical species in the acetonitrile phase depended on water contents in the acetonitrile phase. Similarly, potassium chromate W and potassium permanganate were extracted into acetonitrile phase and potassium was extracted in the presence
… More
of 18-crown-ether without picrate ion. However, the aqueous mixture of 1,4-dioxane could not extract of the charged metalloporphyrins.
2. In order to elucidate the phase separation phenomenon of homogeneous mixed-solution and the different behavior of acetonitrile and 1,4-dioxane, we studied micro-solvent structures of the mixed solvents by X-ray diffraction and small-angle neutron scattering (SANS) methods. Both methods indicate the formation of solvent clusters at 0.2 【less than or equal】 X_<AN> 【less than or equal】 O.6 in mole fraction rang for acetonitrile-water mixtures. For the mixture of 1,4-dioxane and water, solvent clusters are formed, but water strongly hydrates to 1,4-dioxane molecules, resulting in the formation of small 1,4-dioxane clusters. SANS results indicate the solvent aggregation by addition o f NaCl and the growth of clusters with increase of NaCl. When the formation of cluster reaches to a maximum size, phase separation occurs.
3. Raykeigh light-scattering experiments also suggest the solvent cluster formation in the mixed solutions of water and water-soluble organic solvents.
4. It has been clarified by fluorospectrophotometry that chemical species dissolved in homogeneous mixed-solvents are preferentially solvated: hydrophobic compounds are solvated by organic solvents molecules and ionic species are solvated by water molecules. Water-soluble indicators are solvated by both water and organic solvent molecules. Less
|
