Standard Gibbs energy change solvent

In contrast to this early empirical solvent scale, one of the more recent, introduced by Eliel and Hofer in 1973 [25] and based on the solvent-dependent conformational equilibrium of 2-z-propyl-5-methoxy-l,3-dioxane, should be mentioned cf. Table 4-9 in Section 4.4.3). In general, polar solvents shift this conformational equilibrium towards the more dipolar axial cis isomer. The authors proposed calling the standard molar Gibbs energy changes associated with this equilibrium, he D scale D for... 

IR based empirical solvent polarity parameter (Schleyer and Allerhand) standard molar Gibbs energy change standard molar Gibbs energy of activation... 

The rate constant (kst) of the electron transfer reaction from an electron donor (D) and an electron acceptor (A) is related to the electron coupling matrix element between D and A, ( V ), standard Gibbs free energy change of the electron transfer step (AG°), and the sum of molecular and solvent reorganization energies (1) by [40]... 

Electromotive force measurements of the cell Pt, H2 HBr(m), X% alcohol, Y% water AgBr-Ag were made at 25°, 35°, and 45°C in the following solvent systems (1) water, (2) water-ethanol (30%, 60%, 90%, 99% ethanol), (3) anhydrous ethanol, (4) water-tert-butanol (30%, 60%, 91% and 99% tert-butanol), and (5) anhydrous tert-butanol. Calculations of standard cell potential were made using the Debye-Huckel theory as extended by Gronwall, LaMer, and Sandved. Gibbs free energy, enthalpy, entropy changes, and mean ionic activity coefficients were calculated for each solvent mixture and temperature. Relationships of the stand-ard potentials and thermodynamic functons with respect to solvent compositions in the two mixed-solvent systems and the pure solvents were discussed. 

Equation (31) expresses the dependence of the relative rate (equilibrium) constant on the properties of the solvent characterized by the parameters Ap and Sp. The parameter Rp is proportional to the differences between the relative Gibbs free energies for the nth and sth solvent of the given and standard substrates. The parameter Sp characterizes the effect of a change of the substrate on the rate constant of the substrate with a standard substituent. In the Hammett equation this substituent is represented by hydrogen for which a was definitionally put equal to zero, while in the Taft and Taft-Pavelich equations methyl is used as the standard substituent [a = = 0). 

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