A
solvent parameter defined by:
derived from the Gibbs energy of transfer
(

) of a series of solutes from water to numerous aqueous-organic mixtures and to pure
solvents:
where

is a solute parameter,
and

and

characterize the solvent. The

values are used to define a solvent solvophobic effect so that

values are scaled
from unity (water) to zero (hexadecane).
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1165