Thermodynamics of transfer of Ph4C; scaled-particle theory and the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (15) ◽  
pp. 2004-2009 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Total Free Energy ◽  
Scaled Particle Theory ◽  
Free Energies ◽  
Particle Theory ◽  
Free Energy Of Transfer ◽  
Enthalpy And Entropy ◽  
Interaction Term ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

Free energies of transfer of Ph4C from acetonitrile to 20 other solvents have been calculated from literature data. The contribution of the cavity term to the total free energy has been obtained from scaled-particle theory and Sinanoglu–Reisse–Moura Ramos theory. It is shown that there is little connection between the cavity term and the total free energy of transfer, and that there must be, in general, a large interaction term. If the latter is important for transfer of Ph4C, we argue that it must also be important for transfer of the ions Ph4As+ and Ph4B−. Previous suggestions that the interaction term is zero for transfer of these two ions are thus seen to be unreasonable. We also show, for six solvents, that the interaction term for Ph4C is very large in terms of enthalpy and entropy, and that scaled-particle theory seems not to apply to transfers of Ph4C between pure organic solvents.The free energy, enthalpy, and entropy of transfer of Ph4As+ = Ph4B− have been calculated by dividing the total transfer values into neutral and electrostatic contributions; reasonable agreement is obtained between calculated and observed values.

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

1977 ◽  
Vol 55 (4) ◽  
pp. 682-685 ◽  
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.

scholarly journals Use of scaled-particle theory in the assessment of the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Recent Work ◽  
Scaled Particle Theory ◽  
Cavity Formation ◽  
Energy Term ◽  
Free Energies ◽  
Particle Theory ◽  
Novel Method ◽  
Energy Of Interaction ◽  
Solvent Molecules

A novel method for the assessment of the Ph4As+/Ph4B− assumption for free energies of transfer of single ions has recently been suggested by Treiner, and used by him to deduce that the assumption is not valid for transfers between water, propylene carbonate, sulpholane, dimethylsulphoxide, N-methyl-2-pyrrolidone, and perhaps also dimethylformamide. The basis of the method is the estimation of the free energy of cavity formation by scaled-particle theory, together with the hypothesis that the free energy of interaction of Ph4As+ (or Ph4B−) with solvent molecules is the same in all solvents, ΔGt0(int) = 0. It is shown in the present paper that (a) whether or not the Ph4As+/Ph4B− assumption applies to transfer to a given solvent depends on which other solvent is taken as the reference solvent in Treiner's method, (b) the calculation of the cavity free energy term by scaled-particle theory and by the theory of Sinanoglu – Reisse – Moura Ramos (SRMR) yields values so different that the method cannot be considered reliable, (c) the calculation of cavity enthalpies and entropies for Ph4As+ or Ph4B− by scaled-particle theory yields results that are chemically not reasonable, (d) the hypothesis that ΔGt0(int) = 0 conflicts with SRMR theory, and (e) the conclusions reached by Treiner are not in accord with recent work that in general supports the Ph4As+/Ph4B− assumption for solvents that are rejected by Treiner.

Comparison of the free energy of transfer of electrolytes, measured with cells without transference, with the sum of the free energies of the corresponding cations and anions with the Owen-cell on standard conditions

1983 ◽  
Vol 36 (10) ◽  
pp. 1997 ◽  
Author(s):  
K Schwabe ◽  
W Hoffmann ◽  
C Queck
Keyword(s):  
Free Energy ◽  
Free Energies ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Ph Values ◽  
Liquid Junction Potentials ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Very High ◽  
Junction Potential

The comparison of S2ΔS1G°tr(E1) with the sum of the values for the corresponding cation and anion S2ΔS1G°tr(Ct+)~S2ΔS1G°tr(X-) (measured) with Owen cells, gained by double extrapolation and by the assumption that the liquid junction potential at 1→0 may be neglected) gives values which differ by not more than ±5%. Most of the investigated acids allow the conclusion that the pH values, measured in cells with transference, and having the same electrodes, give good information on the acidity of the organic solvent and its water mixtures, referred to the standard state in water. That means that the pH, changed to the same H+ concentration in the solvent compared with that in water, is essentially an effect of the free energy of transfer of the hydrogen ion and not of very high liquid junction potentials.

Concerning the distant polar interaction in free energies of transfer. An explanation and an estimation procedure

1991 ◽  
Vol 69 (12) ◽  
pp. 1893-1903 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Free Energy ◽  
Hydrogen Bonding ◽  
Estimation Procedure ◽  
Free Energies ◽  
Polar Interaction ◽  
Free Energies Of Transfer ◽  
Polar Groups ◽  
Polyfunctional Compounds ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

For polyfunctional compounds, free energies of transfer from gas to aqueous solution require corrections for the interactions of polar groups (Distant Polar Interactions). These corrections can be made with very few adjustable parameters by using a model of the solvation process assuming hydrogen bonding is the major source of the effect on free energy of transfer for polar groups, and that hydrogen bonding is perturbed by polar effects, measured by Taft σ*. Parameters evaluated for polyfluoro, polychloro, and polybromo compounds successfully predicted the free energies of transfer for mixed polyhalogen compounds. Preliminary parameters have been evaluated for ethers, amines, phenyl groups, nitriles, and esters. Key words: free energy of transfer, distant polar interaction, hydrogen bonding, solvation.

scholarly journals HYDROPHOBIC EFFECTS IN WATER AND WATER/UREA SOLUTIONS A COMPARISON

1994 ◽  
Vol 2 (2) ◽  
pp. 71-82
Author(s):  
E. A. Lissi ◽  
E. B. Abuin
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Alkyl Chain ◽  
Standard Free Energy ◽  
The Other ◽  
Standard Entropy ◽  
Simple Description ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

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.

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

1973 ◽  
Vol 51 (18) ◽  
pp. 3051-3061 ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document