Note on standard free energy of transfer and partitioning of ionic species between two fluid phases

The partition of several n-alkanols, from methanol to n-nonanol, between n-hexane and water and between n-hexane and water containing 20 % (w/v) urea has been measured at temperatures ranging from 0 °C to 60 °C. The standard free energy of transfer from water to the urea-containing solution decreases with the length of the alkyl chain, being positive for the small alcohols and negative for the higher alkanols. The same tendency is observed upon all the temperature range considered. On the other hand, the standard entropy of transfer from water to the urea-containing solution increases with the length of the alkyl chain of the alkanol. These results are compatible with a simple description of the urea effect in terms of increasing the entropy of dissolution of the hydrophobic alkyl chain in the aqueous solution.

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Thermodynamic Properties of Aqueous Organic Solutes in Relation to Their Structure. Part I. Free Energy of Transfer from H2O to D2O for a Series of Isomeric Ketones

Canadian Journal of Chemistry ◽

10.1139/v73-455 ◽

1973 ◽

Vol 51 (18) ◽

pp. 3051-3061 ◽

Cited By ~ 12

Author(s):

Carmel Jolicoeur ◽

Ghislain Lacroix

Keyword(s):

Free Energy ◽

Standard Free Energy ◽

Scaled Particle Theory ◽

Cavity Formation ◽

Degree Of Branching ◽

Structural Part ◽

Hydrocarbon Chains ◽

Free Energy Of Transfer ◽

Energy Of Transfer ◽

Heats Of Transfer

The solubilities of 18 decanones have been measured in H2O and D2O at 25 °C from their u.v. absorption spectra. The data were used to calculate ΔGt0, the standard free energy of transfer of these solutes from H2O to D2O ΔGt0 was found negative for the saturated ketones, but positive for most of the unsaturated and polycyclic isomers. A rough correlation was observed between ΔGt0 and the degree of branching in the hydrocarbon chains of the ketones: ΔGt0 increases with the degree of branching. From the temperature dependence of ΔGt0 obtained at 10, 25, and 40 °C, heats of transfer ΔHt0 were determined for typical ketones, namely 2-decanone and adamantanone. ΔHt0 was found as −2.1 kcal mol−1 for 2-decanone and ~0 ± 0.5 kcal mol−1 for adamantanone.The results are discussed in terms of two main contributions: (1) an isotope effect in the free energy of cavity formation and (2) perturbation of solvent structure by the solutes, differing in H2O and D2O. Using the scaled-particle theory to evaluate the former, the variations in the observed ΔGt0 are assigned to the structural part of ΔGt0.

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Use of the scaled-particle theory for the determination of single ion standard free energy of transfer between solvents

Canadian Journal of Chemistry ◽

10.1139/v77-096 ◽

1977 ◽

Vol 55 (4) ◽

pp. 682-685 ◽

Cited By ~ 16

Author(s):

Claude Treiner

Keyword(s):

Free Energy ◽

Mixed Solvents ◽

Standard Free Energy ◽

General Rule ◽

Scaled Particle Theory ◽

Particle Theory ◽

Solvent Interactions ◽

Free Energy Of Transfer ◽

Energy Of Transfer

The tetraphenylboron extrathermodynamic assumption is one of the methods most often used for the evaluation of single ion standard thermodynamic functions of transfer between two solvents. We show in this article that the scaled-particle theory may be useful for discriminating among those solvents for which this extrathermodynamic assumption may be questionable because of strong solute–solvent interactions. Although no general rule is proposed, the tetraphenylboron assumption seems valid in the case of the free energy of transfer between water and solvents like methanol, ethanol, acetonitrile, and formamide; it should not be used in the case of the transfer to solvents like propylene carbonate, dimethylsulfoxide or sulfolane. The scaled-particle theory may also be used to predict within 20% the standard free energy of transfer of the tetraphenylboron ion between water and aqueous mixed solvents; examples are given for water–methanol and water–ethanol mixtures.

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