Reactant Solvation

It should always be home in mind that solvent effects can modify the energy of both tile reactants and the transition slate. It is the difference in the two solvation effects that is the basis for changes in activation energies and reaction rates. Ihus, although it is conimon to express solvent effects solely in terms of reactant solvation or transition-slate solvation,... 

Kinetic parameters of zinc electrode processes in water-organic mixtures depend strongly on the composition of the surface layer, which is modified by the adsorption of organic solvent on the electrode and also on reactant solvation [46], which is changing with a solvent composition. 

Most treatments of such double-layer effects assume that the microscopic solvation environment of the reacting species within the interfacial region is unaltered from that in the bulk solution. This seems oversimplified even for reaction sites in the vicinity of the o.H.p., especially since there is evidence that the perturbation of the local solvent structure by the metal surface [18] extends well beyond the inner layer of solvent molecules adjacent to the electrode [19]. Such solvent-structural changes can yield considerable influences upon the reactant solvation and hence in the observed kinetics via the work terms wp and wR in eqn. (7a) (Sect. 2.2). While the position of the reaction site for inner-sphere processes will be determined primarily by the stereochemistry of the reactant-electrode bond, such solvation factors can influence greatly the spatial location of the transition state for other processes. 

The Change of Reactant Solvation and the Potential of Redox Systems... 

Therefore, in order to explain the influence of mixed solvents on the course of electrochemicEil reactions, information about the reactant solvation and the composition of the electrode surface layer should be available. 

The rate of reaction for electron transfer depends on many factors, including the rate of substitution in the coordination sphere of the reactants, the match of energy levels of the two reactants, solvation of the two reactants, and the nature of the ligands. 

The reaction is faster in DMSO-water than in ethanol-water. Reactant solvation can be separated from transition state solvation by calorimetric measurement of the heat of solution of the reactants in each solvent system. The data in Figure 3.36 compare the energies of the reactants and TS for ethyl acetate and hydroxide ion reacting in aqueous ethanol versus aqueous DMSO. It can be seen that both the reactants and the TS are more strongly solvated in the ethanol-water medium. The enhancement... 

Reactant Solvation. A great deal has been written about reactant solvation and transition-state solvation for a wide variety of reactions. We shall deal first with the quantitative attempts that have been made to discuss reactivities in terms of solvent effects on thermodynamic properties of solvated species, and then briefly touch on a range of systems where the discussion is of a more qualitative or hypothetical nature. 

Thus, to obtain the free-energy curve Gr associated with the reactant simulation one can use the differences in the solute-water interaction energies, (Usw), between the diabatic states of the solute in its reactant (R) and transition state (TS) structures for a broad set of configurations of solvent molecules around the solute in a molecular dynamics simulation of the reactant solvation ... 

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