Effects of substituent on the thermodynamic functions of ionisation of ortho-substituted phenols

Abstract

Thermodynamic ionisation constants of o-chlorophenol, o-bromophenol, o-iodophenol and o-ethoxyphenol have been measured spectrophotometrically over the temperature range 5–50°. From these measurements values for the standard free energy, enthalpy, and entropy of their ionisation have been calculated. A detailed analysis of substituent effects upon the thermodynamic functions is made in terms of the Taft equations and the equations of Farthing and Nam.