Keto- Enol Tautomerism of 2-Hydroxy Naphthylideneaniline with Lanthanide Shift Reagent Pr(fod)₃in Different Solvents

Abstract

Aldamines derived from the aromatic aldehydes having a hydroxyl group in the ortho position to aldehyde group are of interest mainly due to existence of either O-H-N or O-H-N type of intramolecular hydrogen bond and the related tautomerism between such enol-imine and ketoamine forms. [1][2][3][4] The electron withdrawing or donating ability of the N-substitunts, their position and stereochemistry, as well as hydrogen bond donoracceptor properties, can stabilize one or another tautomer in the crystal. 2,5 The spectra of different schiff-bases have been studied in polar and non-polar solvents and ABSTRACT Addition of Lanthanide shift reagents Pr(fod) 3 to 2-hydroxynaphthylideneaniline in non polar solvents and slightly polar solvent showed for the first time a keto-enol tautomerism. K T values= ([keto]/[enol]) were calculated in the chosen solvents. K T at fixed con centration of the shift reagent was determined at different temperatures and the thermodynamic parameters (ΔH°, ΔG°, ΔS°) were obtained.