Abstract
The solvation free energy of an ion in an organic solvent is calculated using our new electrostatic method, and is combined with the hydration free energy to yield the free energy of transfer of the ion from water to the organic solvent. It is shown that for the solvent systems water/1,2-dichloroethane, dichloromethane, chloroform, o-dichlorobenzene, chlorobenzene, and nitrobenzene there is good agreement between the calculated ΔGto values and the free energies for partition of ions, ΔGpo = -RTlnP. For organic phases in which water is quite soluble, for example 1-octanol, 1-pentanol, isopentanol, ethyl acetate, and methylisobutylketone, the calculated ΔGto values are always more positive than the observed partition values, ΔGpo. It is shown that this effect is due to hydration of the ions in the wet organic phase and by calculations on a solvation model in which an ion in the wet organic phase is surrounded by a layer of water of thickness 3.1 Å (the diameter of a water molecule) it is concluded that in the first group of solvents most ions are unhydrated in the wet organic phase; Cl- is an exception and is partially hydrated. In the second group of wet solvents, all ions are at least partially hydrated, and Cl- is hydrated by a layer of water that must be even thicker than the diameter of a water molecule.
| Original language | English |
|---|---|
| Pages (from-to) | 143-151 |
| Number of pages | 9 |
| Journal | Journal of Inorganic and Nuclear Chemistry |
| Volume | 43 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1981 |
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Calculations on ionic solvation-V The calculation of partition coefficients of ions. / Abraham, Michael H.; Liszi, J.
In: Journal of Inorganic and Nuclear Chemistry, Vol. 43, No. 1, 1981, p. 143-151.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Calculations on ionic solvation-V The calculation of partition coefficients of ions
AU - Abraham, Michael H.
AU - Liszi, J.
PY - 1981
Y1 - 1981
N2 - The solvation free energy of an ion in an organic solvent is calculated using our new electrostatic method, and is combined with the hydration free energy to yield the free energy of transfer of the ion from water to the organic solvent. It is shown that for the solvent systems water/1,2-dichloroethane, dichloromethane, chloroform, o-dichlorobenzene, chlorobenzene, and nitrobenzene there is good agreement between the calculated ΔGto values and the free energies for partition of ions, ΔGpo = -RTlnP. For organic phases in which water is quite soluble, for example 1-octanol, 1-pentanol, isopentanol, ethyl acetate, and methylisobutylketone, the calculated ΔGto values are always more positive than the observed partition values, ΔGpo. It is shown that this effect is due to hydration of the ions in the wet organic phase and by calculations on a solvation model in which an ion in the wet organic phase is surrounded by a layer of water of thickness 3.1 Å (the diameter of a water molecule) it is concluded that in the first group of solvents most ions are unhydrated in the wet organic phase; Cl- is an exception and is partially hydrated. In the second group of wet solvents, all ions are at least partially hydrated, and Cl- is hydrated by a layer of water that must be even thicker than the diameter of a water molecule.
AB - The solvation free energy of an ion in an organic solvent is calculated using our new electrostatic method, and is combined with the hydration free energy to yield the free energy of transfer of the ion from water to the organic solvent. It is shown that for the solvent systems water/1,2-dichloroethane, dichloromethane, chloroform, o-dichlorobenzene, chlorobenzene, and nitrobenzene there is good agreement between the calculated ΔGto values and the free energies for partition of ions, ΔGpo = -RTlnP. For organic phases in which water is quite soluble, for example 1-octanol, 1-pentanol, isopentanol, ethyl acetate, and methylisobutylketone, the calculated ΔGto values are always more positive than the observed partition values, ΔGpo. It is shown that this effect is due to hydration of the ions in the wet organic phase and by calculations on a solvation model in which an ion in the wet organic phase is surrounded by a layer of water of thickness 3.1 Å (the diameter of a water molecule) it is concluded that in the first group of solvents most ions are unhydrated in the wet organic phase; Cl- is an exception and is partially hydrated. In the second group of wet solvents, all ions are at least partially hydrated, and Cl- is hydrated by a layer of water that must be even thicker than the diameter of a water molecule.
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U2 - 10.1016/0022-1902(81)80451-4
DO - 10.1016/0022-1902(81)80451-4
M3 - Article
VL - 43
SP - 143
EP - 151
JO - Polyhedron
JF - Polyhedron
SN - 0277-5387
IS - 1
ER -