There are three Kamlet-Taft solvent parameters: α (hydrogen bond donor),
β (hydrogen bond acceptor), and π*
(polarizability).
The values of α have been set to 0 for solvents that are assumed to be unable to donate hydrogen bonds.
This truncation at 0 is the main reason it differs from other measures of hydrogen bond acidity such as ET and AN.
Occasionally a "polarity correction term" (fudge factor), δ, is seen in correlations.
For aromatics δ=1.0, for polychlorinated compounds δ=0.5, and for all other solvents δ=0.0 .
If possible this type of ad hoc parameters should be avoided and separate correlations used for different solvent classes.
α is correlated with →Dimroth-Reichardt ET
(→ET vs α) and
→Gutmann AN
(→AN vs α).
β is correlated with →Gutmann DN
(→DN vs β) except for amines and sulfides.
π* is correlated with →Catalán SPP
(→SPP vs π*).