Continuum and simple molecular approach to describe solvent polarity for real polar organic solvents

A comparison has been made between the relative permittivity function f(epsilon) and the molecular parameter beta resulting from the dielectric theory, both applied as expressing solvent polarity, the former in the continuum approach and the latter in a very simple molecular approach (beta, similar to the gamma coefficient of the dielectric theory, is proportional to mu(2)/V; mu is the electric dipole moment and V the molar volume). It has been shown that the application of the molecular parameter beta instead of permittivity in the analysis of solvent effects could be more appropriate as it enables (within the individual classes of solvents) linear correlations between beta and parameters characteristic for kinetics or spectral data to be obtained.