Hydrogen bonding. 32. An analysis of water-octanol and water-alkane partitioning and the delta log P parameter of seiler.
A general linear solvation energy equation has been used to analyze published partition coefficients in the systems water-octanol (613 solutes), water-hexadecane (370 solutes), water-alkane (200 solutes), and water-cyclohexane (170 solutes). The descriptors used in the equation are R2, an excess molar refraction; phi H2, the solute dipolarity/polarizability; sigma alpha H2 and sigma beta H2, the effective solute hydrogen-bond acidity and basicity; and Vx, the characteristic volume of McGowan. It is shown that the water-octanol partition coefficient is dominated by solute hydrogen-bond basicity, which favors water, and by solute size, which favors octanol, but solute excess molar refraction and dipolarity/polarizability are also significant. For the water-alkane partition coefficients, the same factors are at work, together with solute hydrogen-bond acidity as a major influence that favors water. An analysis of 288 delta log P values shows that solute hydrogen-bond acidity is the major factor but that solute hydrogen-bond basicity and, to a lesser extent, solute dipolarity/polarizability and size are also significant factors that influence the delta log P parameter.
Abraham
M H
MH
Department of Chemistry, University College London, UK.
Chadha
H S
HS
Whiting
G S
GS
Mitchell
R C
RC
D000473:Alkanes / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006860:Hydrogen Bonding; D000442:Octanols / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry*
D000473:Alkanes; D000442:Octanols; D014867:Water