Definition of Z-value

1. An index of the ionizing power of a solvent based on the frequency of the longest wavelength electronic absorption maximum of 1-ethyl-4-methoxycarbonylpyridinium iodide in the solvent. The Z-value is defined by

   Z = 2.859 x 104/

   where Z is in kcal mol-1 and is in nm.

   KOSOWER (1958). See also Dimroth-Reichardt ET parameter, Grunwald-Winstein equation.