On Coulombic and Solvophobic Liquid‐Liquid Phase‐Separation in Electrolyte Solutions

Wiley - Tập 95 Số 12 - Trang 1579-1586 - 1991
Hermann Weingärtner1, Thomas Merkel1, Ulrich Maurer1, Jörg‐Peter Conzen1, H. Glasbrenner1, Stefan Käshammer1
1Institut für Physikalische Chemie und Elektrochemie der Universität Karlsruhe, Kaiserstraße 12, D‐7500 Karlsruhe, Germany

Tóm tắt

AbstractWe have performed a systematic study of liquid‐liquid phase equilibria in aqueous and non‐aqueous solutions of tetraalkylammonium salts up to about 500 K, covering a large number of hydrogen‐bonding, dipolar aprotic and non‐polar solvents. There appear to be two different types of liquid‐liquid phase equilibria resulting from long‐range Coulombic and from short‐range specific forces, respectively. These may be denoted as Coulombic and solvophobic unmixing. Coulombic unmixing is observed in solutions of 1:1‐electrolytes in solvents of low dielectric constant, as is exemplified for solutions in hydrocarbons and long‐chain alcohols. It appears to be closely related to a general instability of ionic fluids at low reduced temperatures. Increase of the dielectric constant results in complete miscibility, as is demonstrated for salts dissolved in short‐chain alcohols and some common dipolar aprotic solvents. Solvophobic unmixing occurs if salts with large cations and anions are dissolved in water. A phenomenological analysis shows that this phase separation results from those thermodynamic pecularities which are usually attributed to the hydrophobic nature of the cations. Some cation‐anion association appears also to play a role. Similar immiscibilities have been observed with other hydrogen‐bonding solvents of high cohesive energy density, namely glycerol, ethylene glycol, 1,3‐propanediol, formamide and monoethanolamine, suggesting the existence of a more general solvophobic unmixing effect.

Từ khóa


Tài liệu tham khảo

10.1002/bbpc.19890931004

10.1063/1.437159

10.1021/ar00178a003

10.1007/BF00675109

10.1080/00268978700100711

10.1016/0022-1902(61)80258-3

10.1021/je00028a023

Valyashko V. M., 1983, Dokl. Akad. Nauk USSR, 272, 390

Urusova M. A., 1983, Russ. J. Inorg. Chem. (engl. transl.), 28, 1039

10.1021/j100815a007

10.1021/j100256a006

10.1021/ja00947a023

10.1016/0022-1902(79)80488-1

10.1021/j100346a002

10.1021/j100376a037

10.1021/j100638a009

10.1146/annurev.pc.32.100181.001143

Tissot P., 1983, Molten Salt Techniques, 137

Gordon J. E., 1969, Techniques and Methods of Organic and Organometallic Chemistry, 52

Franzosini P., 1980, Thermodynamic and Transport Properties of Molten Salts

10.1002/bbpc.19900940330

Wen W.‐Y., Water and Aqueous Solutions

Huot J. Y., 1985, The Chemical Physics of Solvation, 417

10.1007/978-1-4684-1959-7

10.1021/ja00234a039

10.1021/jo00155a003

10.1021/jo01019a060

10.1021/j100288a041

Rowlinson J. S., 1982, Liquids and Liquid Mixtures

10.1021/ja01157a047

10.1039/dc9776400188

10.1063/1.458263

H.Weingärtner S.Wiegand andW.Schröer J. Chem. Phys. submitted.

Hildebrand J. H., 1964, The Solubility of Non‐Electrolytes

10.1021/j150657a005

10.1021/ja01333a026

W. A.PriceandH.Weingärtner J. Phys. Chem. in press.

S.KäshammerandH.Weingärtner to be published.

10.1007/BF00645104

10.1016/0021-9614(83)90076-9

Millero F. J., 1972, Water and Aqueous Solutions

Kreis R. W., 1971, J. Phys. Chem., 75, 210

U.MaurerandH.Weingärtner to be published.

10.1039/tf9686402146

10.1039/fs9821700093

10.1063/1.1677736

Goldmann G., 1976, Z. Naturforsch., 31, 769, 10.1515/zna-1976-0715

Thông tin
Thông tin xuất bản

Wiley

Tập 95 Số 12

1579-1586

Thông tin tác giả