Calculation of Gurney parameters for aqueous tetraalkylammonium halides based on Friedman's cosphere-overlap model

Streng, William H.; Wen, Wen-Yang

doi:10.1007/bf00647941

Cited by 20 publications

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“…They fit model potentials simultaneously to excess free energy data and to conductivity data for alkali halides and tetraalkyl ammonium halides in a vast least squares loop using approximation methods that they have devised for the purpose. This approach is still in development but the results announced so far are mostly consistent with those reported by Friedman et al (b8) and, for R4NX salts, by Wen and Streng (61).…”

Section: Short Range Behavior Of the Ion-ion Gab(r)--as Soonsupporting

confidence: 87%

The “Structure” of Electrolyte Solutions, 1952–1977

Friedman

1977

J. Electrochem. Soc.

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unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP VoL 124, No. 12 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP

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Section: Short Range Behavior Of the Ion-ion Gab(r)--as Soonsupporting

confidence: 87%

The “Structure” of Electrolyte Solutions, 1952–1977

Friedman

1977

J. Electrochem. Soc.

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“…This behavior follows if various hydrophobic particles affect the water in their cospheres similarly, in which case the principal size effects in l7ij enter through the size dependence of CORij(r) and Vmu(r). [4][5][6][7][8] Further discussion of the model assumptions is provided in the earlier ~o r k~-~ and references given there. Here we exploit the fact, not assumed but observed, that the A, parameters needed to fit the thermodynamic data are found in a certain range in cases in which particles i and j are hydrophobic or, at least, carry relatively hydrophobic groups.…”

Section: ( 5 )mentioning

confidence: 99%

“…Even when i and j are both ions and Bij does not exist, the A, coefficients can be determined by fitting the model to appropriate experimental data. [4][5][6][7][8] This model follows from a very simple physical picture which neglects a number of known effects, some of which are mentioned below. The neglected effects will contribute to the Gurney Aij parameters determined by fitting the models to experimental data.…”

Section: ( 5 )mentioning

confidence: 99%

Benzene-benzene interaction in aqueous solution

Rossky¹,

Friedman

1980

J. Phys. Chem.

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Publication costs assisted by the National Science FoundationIt is shown that the recently measured deviation from Henry's law for solutions of benzene in water is in reasonable agreement with what. would be predicted from certain models for the solute-solute potential of mean force, with parameters chosen in accordance with earlier results for other hydrophobic solutes. The corresponding inference for the temperature dependence of the model benzenebenzene potential predicts a negative temperature derivative for the osmotic second virial coefficient.Recently Tucker and Christian' reported new results for the equilibrium distribution of benzene between vapor and aqueous solution phases, showing measurable deviations from Henry'n law. As they point out, the deviation is in the direction iaxpected if painvise hydrophobic bonds2 form between benxene molecules in solution. Their result for the corresponding standard free energy of association on the mole fraction scale is about -2300 cal/mol, which is considerably less negative then an estimate given earlier by Ben-Naim and c o -~o r k e r s .~The purpose of this note is to show that the new measurements are roughly predictable based on earlier theoretical considerations of related s o l u t i o n~,~-~ and, further, that these measurements provide a relatively sensitive test of the theoretical model.To relate the new data to earlier studies of the interaction of hydrophobic solutes in water, it is convenient to introduce the corresponding osmotic (McMillan-Mayer) second virial coefficientgJOwhere Uij(r) is the effective (solvent-averaged and orientation-averaged4) potential of mean force between solute particles i and j at a separation r, 0 = l/kBT, and kg is Boltzmann's constant. The experimental Henry's law "constant" KHB for benzene is satisfactorily represented (2) where XB is the mole fraction of benzene. The pairwise benzene-benzene (BB) interaction is then reflected by thewhere pw is the number density of the pure solvent, UB the partial molal volume of benzene at infinite dilution (82.3 cm3), and u, is the molar volume of pure water. Tucker and Christian report' K1 = 87 corresponding to BBB = -1177 A3.It may be of interest to note that for benzene in the gas phase at 35 O C the second virial coefficient id1 about -2100A3, corresponding to a more negative free energy of association than in solution. The comparison is, however, not very direct. The attractive part of the solvent-averaged pair potential results from solvent structural effects as well as solvent-mediated dispersion forces while, in the gas phase, the attractive part of the pair potential results by1 KHB = ko + k l X B K, =' -k,/ko = -2pwBBB -1 + 2 u B / u w TX 78712. 0022-3654/80/2084-0587$0 1 .OO/Q mostly from unattenuated dispersion forces.It also may be noted that if UBB were replaced by the interaction potential of two hard spheres, each of diameter uBB = 6 A3, corresponding roughly to a benzene molecule,6 we would have BBB = 452 A3. The difference, about -1629 A3, is a measure of the attracti...

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“…Estimates of pairwise interactions of two nonpolar solutes are obtained from osmotic second virial coefficients in aqueous solutions, BAB(aq), which are a measure of the tendency of two molecules to associate above and beyond the association that would be present in a random solution of A and B in water (1,(15)(16)(17)(18)(19)(20)(21)(22). For strongly associating species BAA(aq) becomes equal to minus the ordinary thermodynamic association constant [-K2(aq)].…”

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confidence: 99%

Differences between pair and bulk hydrophobic interactions.

Wood

Thompson

1990

Proc. Natl. Acad. Sci. U.S.A.

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It is now well known that the pair interaction between two hydrocarbon molecules in water has distinctly different properties from the bulk hydrophobic interaction familiar to the biochemist, which is modeled by the transfer of a hydrocarbon from aqueous solutions to pure liquid hydrocarbon. We consider experimental data for pair interactions, which have been fitted by a simple empirical potential function, and point out some of their properties. (i) Surface free energy and cosphere overlap models, of the type considered until now, cannot reproduce correctly both the pair and bulk hydrophobic interactions. (ii) Pair interactions though still attractive are strikingly weaker in aqueous solution than in the gas phase, in contrast to the usual view of hydrophobic interactions. (iii) For pair interactions in water, the solvent-separated configuration is less important than the contact configuration if the hydrocarbon has more than two carbon atoms.Hydrophobic "bonding" involves the association of nonpolar groups in an aqueous environment. Kozak et al. (1) have drawn the distinction between bulk hydrophobic interactions-that is, "interactions involving large clusters of nonpolar groups as may, for instance, be found in the interior of a protein molecule"-and interactions between small numbers of nonpolar groups as may, for instance, be found at the surface of a protein molecule. These qualitatively different interactions are generally lumped together in the analysis of biochemical systems. For macromolecules, models of bulk hydrophobic interactions are appropriate for the buried molecular interior, while models for pair hydrophobic interactions are probably more appropriate at the molecular surface where there are many neighboring water molecules present. The distinction between these two kinds of interactions is important because they can be quite different in magnitude. As described below, the relative effect of water, in general, is to increase the bulk interaction and decrease the pair interaction for saturated hydrocarbons, although both are decreased for benzene. The macroscopic features of both bulk and pair hydrophobic interactions have been extensively studied and much is known about them (2-23). At the molecular scale a knowledge of aqueous hydrophobic interactions implies a knowledge of the potentials of average force between the hydrophobic species, and many questions about these potentials remain unanswered. For a complete understanding of these interactions in biochemical processes, we need a detailed knowledge of the forces involved. This paper presents some conclusions about the effects of water on bulk and pair interactions of hydrophobic molecules and suggests some tests of molecular scale models of these interactions. Pair Versus Bulk InteractionsThe relationships between pair interactions, bulk interactions, hydrophobic solvation, and the transfer of hydrophobic groups between water and hydrophobic medium is illustrated by the following thermodynamic cycle. nR(g, c@) AG,(g, Ce) IR (g co)H...

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Calculation of Gurney parameters for aqueous tetraalkylammonium halides based on Friedman's cosphere-overlap model

Cited by 20 publications

References 10 publications

The “Structure” of Electrolyte Solutions, 1952–1977

The “Structure” of Electrolyte Solutions, 1952–1977

Benzene-benzene interaction in aqueous solution

Differences between pair and bulk hydrophobic interactions.

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