TY - JOUR
T1 - Anion solvation properties of protic solvents. 2. Salt distribution study
AU - Marcus, Y.
AU - Pross, E.
AU - Hormadaly, J.
PY - 1980
Y1 - 1980
N2 - Standard Gibbs free energies of transfer of chloride anions from water to organic solvents ΔG°tr(Cl-,H2O→S), based on the tetraphenylarsonium tetraphenylborate extrathermodynamic assumption, have been selected from the data in the literature, and correlated with the solvent index ET. The expression ΔG°tr(Cl-,H2O→S)/(RT ln 10) = (29.5 ± 1.4) - (0.116 ± 0.007)(ET/kJ mol-1) is found to express the data sufficiently well, so that ΔG°tr could be calculated for a large group of protic solvents for which ET data were recently obtained. Also, the distribution of potassium chloride between dilute solution of crown ethers in these solvents and aqueous solutions was measured, and the standard Gibbs free energies of distribution, ΔG°distr, were obtained. These are related to the former quantities by ΔG°tr(Cl-,H2O→S)/kJ mol-1 = ΔG°distr/kJ mol-1 + (116/∈S) + (29 ± 3) where ∈S is the dielectric constant of the solvent. This semiempirical expression is rationalized in terms of the interactions leading to the distribution equilibrium. Distribution measurements as described here are proposed as a general method for obtaining individual standard Gibbs energies of transfer of anions from water to immiscible solvents.
AB - Standard Gibbs free energies of transfer of chloride anions from water to organic solvents ΔG°tr(Cl-,H2O→S), based on the tetraphenylarsonium tetraphenylborate extrathermodynamic assumption, have been selected from the data in the literature, and correlated with the solvent index ET. The expression ΔG°tr(Cl-,H2O→S)/(RT ln 10) = (29.5 ± 1.4) - (0.116 ± 0.007)(ET/kJ mol-1) is found to express the data sufficiently well, so that ΔG°tr could be calculated for a large group of protic solvents for which ET data were recently obtained. Also, the distribution of potassium chloride between dilute solution of crown ethers in these solvents and aqueous solutions was measured, and the standard Gibbs free energies of distribution, ΔG°distr, were obtained. These are related to the former quantities by ΔG°tr(Cl-,H2O→S)/kJ mol-1 = ΔG°distr/kJ mol-1 + (116/∈S) + (29 ± 3) where ∈S is the dielectric constant of the solvent. This semiempirical expression is rationalized in terms of the interactions leading to the distribution equilibrium. Distribution measurements as described here are proposed as a general method for obtaining individual standard Gibbs energies of transfer of anions from water to immiscible solvents.
UR - http://www.scopus.com/inward/record.url?scp=1542590200&partnerID=8YFLogxK
U2 - 10.1021/j100458a010
DO - 10.1021/j100458a010
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AN - SCOPUS:1542590200
SN - 0022-3654
VL - 84
SP - 2708
EP - 2715
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 21
ER -