Energy of hydration

Van Oss and Good [148] have compared solubilities and interfacial tensions for a series of alcohols and their corresponding hydrocarbons to determine the free energy of hydration of the hydroxyl group they find -14 kJ/mol per —OH group. 

The relative acidities in the gas phase can be detennined from ab initio or molecular orbital calculations while differences in the free energies of hydration of the acids and the cations are obtained from FEP sunulations in which FIA and A are mutated into FIB and B A respectively. 

Jorgenson W L and Ravimohan C 1985 Monte Carlo simulation of the differences in free energy of hydration J. Chem. Phys. 83 3050... 

Fig. 6. Free energies of hydration calculated, for a series of polar and non-polar solute molecules by extrapolating using (3) from a 1.6 ns trajectory of a softcore cavity in water plotted against values obtained using Thermodynamic Integration. The solid line indicates an ideal one-to-one correspondence. The broken line is a line of best fit through the calculated points.

Carlson, H. A., Jorgensen, W. L. An extended linear response method for determining free energies of hydration. J. Phys. Chem. 99 (1995) 10667-10673... 

Carlson H A and W L Jorgensen 1995. An Extended Linear Response Method for Determining Free Energies of Hydration. Journal of Physical Chemistry 99 10667-10673. 

Privalov, P. L., and Makhatadze, G. I., 1993. Contributions of hydration to protein folding thermodynamics. II. The entropy and Gibbs energy of hydration. y(9wra z/ of Molecular Biology 232 660-679. 

The impossibility of x being equal to about 1 V, as suggested by Kamieifki, " " has been demonstrated by Frumkin on the basis of a discussion of the real energies of hydration. Estimates from the variation in the solution surface potential with electrolyte molarity have yielded the value of +0.025 0.010 V.21 For methanol, the same method results in a value of -0.09 V.146 Later the authors of that investigation stated that both estimated values should be understood as the lower limits of surface potentials of water and methanol. "... 

Using molecular mechanics calculations to assess the three-dimensional shape of a molecule, various surface properties such as polarity and size can be calculated. The dynamic molecular surface properties can be determined from the (low energy) conformation(s) of the drug molecule obtained by molecular mechanics calculations of conformational preferences. The potential advantage of this method is that the calculated surface character-sitics determine numerous physicochemical properties of the molecules including lipophilicity, the energy of hydration and the hydrogen bond formation capacity [187-... 

Table 10. Free Energies of Hydration of Anions A and of Acid Dissociation, AH = A" + H+...

Activation Energy of Hydration of Oxides Formed in Various Electrolytes... 

The apparent large differences in the activation energy of hydration for oxides formed in acidic and alkaline solutions reflect the basic differences in the mechanism of oxide growth in these two cases. 

McAllister, M. A., Perczel, P. Csaszar, W. Viviani, J.-L. Rivail, and I. G. Csizmadia. 1993b. Peptide Models 4. Topological Features of Molecular Mechanics and Ab Initio 2D-Ramachandran Maps. Conformational Data for For-Gly-NH2, For-L-Ala-NH2, Ac-l-Ala-NHMe and For-L-Val-NH2. J. Mol. Struct. (Theochem) 288, 161-179. Mehrotra, P. K., M. Mezei, and D. L. Beveridge. 1984. Monte Carlo Determination of the Internal Energies of Hydration for the Ala Dipeptide in the C7, C5, aR, and Pn Conformations. Int. J. Quantum Chem. Quantum Biol. Symp. 11, 301-308. 

Chipot, C. Millot, C. Maigret, B. Kollman, P. A., Molecular dynamics free energy perturbation calculations. Influence of nonbonded parameters on the free energy of hydration of charged and neutral species, J. Phys. Chem. 1994, 98,11362-11372... 

In this second example, we examine simple systems near the water-hexane interface. Specifically, we calculate the difference in the free energy of hydrating a hard-sphere solute of radius a, considered as the reference state, and a model solute consisting of a point dipole p located at the center of a cavity [11]. We derive the formula for A A assuming that the solute is located at a fixed distance z from the interface, and subsequently we examine the dependence of the free energy on z. The geometry of the system is shown in Fig. 2.3. 

Jorgensen, W.L., Ravimohan, C., Monte Carlo simulation of differences in free energies of hydration, J. Chem. Phys. 1985, 83, 3050-3054... 

Henchman, R.H., Essex, J.W., Free energies of hydration using restrained electrostatic potential derived charges via free energy perturbations and linear response, J. Comput. Chem. 1999, 20, 499-510... 

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