Volume change of ion pair formation: Rubidium nitrate and thallium(I) nitrate in water

1974 ◽  
Vol 3 (2) ◽  
pp. 91-102 ◽  
Author(s):  
William L. Masterton ◽  
Harry Welles ◽  
Jonathan H. Knox ◽  
Frank J. Millero
Keyword(s):  
Volume Change ◽  
Ion Pair ◽  
Pair Formation ◽  
Rubidium Nitrate ◽  
Ion Pair Formation

Thermodynamics and mechanism of hydrophobic interaction

1977 ◽  
Vol 30 (4) ◽  
pp. 741 ◽  
Author(s):  
DG Oakenfull ◽  
DE Fenwick
Keyword(s):  
Free Energy ◽  
Volume Change ◽  
Hydrophobic Interaction ◽  
Ion Pairs ◽  
Hydrophobic Hydration ◽  
Partial Molar Volumes ◽  
Hydrocarbon Chain ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation

.In the mixed solvent, 0.1 mole fraction ethanol-water, long-chain decyltrimethylammonium carboxylates form ion pairs. Ion-pair association constants (and hence the free energy of ion-pair formation) can be measured conductometrically. It is possible to separate the hydrophobic from the electrostatic contribution to the free energy of ion-pair formation by systematically varying the hydrocarbon chain length. We report measurements of the free energy of hydrophobic interaction (ΔG°HI) over the temperature range 278-328 K. The value of ΔG°HI becomes more negative (stronger hydrophobic interaction) with increasing temperature. The temperature coefficient of ΔG°HI was used to calculate the enthalpy (ΔH°HI) and entropy (ΔS°HI) of hydrophobic interaction. At low temperature the entropic contribution to the free energy is the larger but ΔH°HI, dominates at temperatures above c. 324 K. The volume change of hydrophobic interaction was similarly estimated from the volume change of ion-pair formation. We obtained values of apparent molar volume of the decyltrimethylammonium carboxylates (over a range of concentrations) from very precise density measurements. These could then be combined with the appropriate ion-pair association constant (from the conductance measurements) to give the partial molar volumes of the free ions and the ion pair. Hydrophobic interaction was found to be accompanied by a substantial increase in volume amounting to 10.2 ± 0.3 ml mol-1 for each pair of interacting methylene groups. Our results support the view that hydrophobic interaction occurs with a further ordering of water molecules over and above that which exists in the hydrophobic hydration layer surrounding an isolated hydrophobic molecule.

Extraction of organic acids by ion-pair formation with tri-n-octylamine

1985 ◽  
Vol 178 ◽  
pp. 189-195 ◽  
Author(s):  
M. Puttemans ◽  
L. Dryon ◽  
D.L. Massart
Keyword(s):  
Organic Acids ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation

scholarly journals Determination of ABT-861 by High-Performance Liquid Chromatography and a Model for Ion-Pair Formation with Trifluoroacetic Acid

1999 ◽  
Vol 37 (6) ◽  
pp. 185-190
Author(s):  
N. Simonzadeh ◽  
B. Levison ◽  
A. Buko ◽  
K. Matuszak ◽  
M. Hanscom
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Trifluoroacetic Acid ◽  
High Performance ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation

Charge-transfer stabilization of molecular bicimers: ion pair formation in diarylmethanes

1988 ◽  
Vol 92 (7) ◽  
pp. 1703-1705 ◽  
Author(s):  
R. J. Locke ◽  
Steve H. Modiano ◽  
E. C. Lim
Keyword(s):  
Charge Transfer ◽  
Ion Pair ◽  
Pair Formation ◽  
Ion Pair Formation
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