Solvent effect on intramolecular proton transfer equilibrium in some N-(Rsalicylidene)-alkylamines

The solvent effect on tautomerism of Schiff bases has been studied by measuring the deuterium isotope effect on their 15N NMR and UV-Vis spectra in different solvents. The interactions of the Schiff bases with solvent molecules are of local character and they vary for the series of solvents under study. The experimental results and PM3 calculations show that the solvent effect on the position of the proton transfer equilibrium depends on the electronic structure of particular Schiff bases.