Quantitative measures of the capability of solvents for interaction with solutes.
Such parameters have been based on numerous different physicochemical quantities,
e.g.
rate constants, solvatochromic shifts in
ultraviolet/
visible spectra, solvent-induced shifts in
infrared frequencies, etc. Some solvent parameters are purely empirical in nature, i.e. they
are based directly on some experimental measurement. It may be possible to interpret
such a parameter as measuring some particular aspect of solvent–solute interaction
or it may be regarded simply as a measure of solvent
polarity. Other solvent parameters are based on analysing experimental results. Such a parameter
is considered to quantify some particular aspect of solvent capability for interaction
with solutes.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1164