Transfer free energies for

To use Eq. (8-57) we require an experimental measure of the transfer free energy for the reactant then Eq. (8-57) permits the transfer free energy for the transition state to be calculated. First, consider this equilibrium process ... 

Table 8-10. Solvent Effects and Transfer Free Energies for the Menschutkin Reaction of Triethylamine and Ethyl Iodide" ...

If we assume that the transfer free energy for X is equal to that for HX, we obtain the last two terms of equation 3 by considering ... 

Gu W, Rahi SJ, Heim V (2004) Solvation free energies and transfer free energies for amino acids from hydrophobic solution to water solution from a very simple residue model. J Phys... 

Figure C3.2.10.(a) Dependence of electron transfer rate upon reaction free energy for ET between biphenyl radical anions and various organic acceptors. Experiments were perfonned with the donors and acceptors frozen into...

Calculation of Conformational Free Energies for a Model of a Bilobal Enzyme Protein kinases catalyze the transfer of phosphate from adenosine triphosphate (ATP) to protein substrates and are regulatory elements of most known pathways of signal transduction. 

However, AG° for this process is the transfer free energy, which we indicate by the symbolism in Eq. (8-58) to make clear the direction of transfer. 

By combining these ions with other counterions, single ion transfer activity coefficients are calculated. By these techniques transfer free energies or activity coefficients have been determined for many ions and nonelectrolytes in a wide variety of solvents.Parker has discussed the extrathermodynamic assumptions that lead to single ion quantities. 

Table 8-8 gives some nonelectrolyte transfer free energies, and Table 8-9 lists single ion transfer activity coefficients. Note especially the remarkable values for anions in dipolar aprotic solvents, indicating extensive desolvation in these solvents relative to methanol. This is consistent with the enhanced nucleophilic reactivity of anions in dipolar aprotic solvents. Parker and Blandamer have considered transfer activity coefficients for binary aqueous mixtures. 

Table 8-10 gives pertinent data for the Menschutkin reaction of triethylamine with ethyl iodide. These reactant molecules are volatile, so their transfer free energies were determined by a gas chromatographic variation of the vapor pressure method. For this reaction Eq. (8-57) is written... 

Figure 8-6. Ploi according to Fig. 8-5 of transfer free energies of the transition state (ordinate) and reactant state (abscissa) for the Menschutkin reaction of triethylamine and ethyl iodide. The reference solvent is N, Af-dimethylformamide (No. 27). Data are from Table 8-10, where the solvents are identified by number. Closed circles are polychlorinated solvents.

One derivation, devised by Ratner and Levine,31 elegant in its simplicity, is based on thermodynamics and TST. They assume that the transition states for Eqs. (10-67)-(10-69)-— AA / BB +, and AB —have components with individual and transferable free energies that is, they assume that the partners are activated independently. We represent the components as G(A f), G(A ), G(B t), and G(B ). Then the free energies of activation for the EE andET reactions are... 

If it is assumed that the total free energy for the transfer of solute X from the gas phase to the stationary phase (with molecular interactions characteristic of Infinite dilution) is the linear sum of the individual free energy contributions to the transfer process then a general expression for the solution process, equation (2.11), can be written as follows... 

From the viewpoint of molecular interactions, the number of fundamentally distinct chromatographic stationary phases is very limited.17 One mechanism for adsorption to the stationary phase is solvophobic, or mobilestationary phase transfer free energy effects, in which the adsorption of an analyte to the stationary phase liberates bound solvent. There is often an accompanying enthalpic component to such binding through dispersion interactions. Another mechanism for adsorption is that of specific interactions,... 

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