Thermodynamic Study of the Tautomerism Schiff Base derived from para-aminophenol by Catalyst

Ortho-Methoxybenzylidene-para-hydroxyaniline, meta-Methoxybenzylidene-para-hydroxyaniline, and para-Hydroxybenzylidene-para-hydroxyaniline, as numbered 1,2,3, were synthesized by standard methods. The chemical structures of these compounds were confirmed previously by physical methods in addition to chemical tests. The tautomerism reactions of the above mentioned imine in this paper required the measurements of ultraviolet absorption spectra of imines under study. The tautomeric equilibrium constants of the Schiff bases under study were determined at five different temperatures ranging from 10°C to 50°C, facilitating the estimation of the equilibrium constants of the tautomerism reactions and the thermodynamic functions, namely ?G, ?H, and ?S, of the Schiff base tautomers.