Physical Factors Contributing to Hydrophobic Constant π

The hydrophobicity constants (μ) of different aromatic substituents have been factored into three major components, a volume factor (MW, or Vw), an electronic factor as represented by dipole moment (μ), and H-bonding factor. The following general equation has been shown to be applicable to a wide range of nonpolar to polar substituents, with only a few notable outliers: π = a · MW (or Vw) - b · HB - c · μ + d. The usefulness and the limitations of such a general correlation are discussed.