Electronic transmission of substituent effects through the tellurophen ring

Abstract

The ionization constants of some 5-substituted tellurophen-2-carboxylic acids in water at 25 °C have been determined potentiometrically. An excellent linear correlation is obtained when the pK_a values are plotted against the σ_p constants. The ρ value (+1·20) is equal, within experimental error, to those for the thiophen and selenophen series, showing that the intensity of transmission of the electronic effects of substituents is substantially the same in the three heteroaromatic systems.