AN IMPROVED AND FACILE SYNTHESIS OF SCHIFF BASES IN AQUEOUS MEDIUM

Abstract

Schiff bases have been used aR precursors and intermediates for the synthesis of a variety of organic compounds useful in analytical, medicinal, polymer and liquid crystalline materials' or as ligand~ for complcxacion. Previously Schiff bases have been synthesized by retluxing the mixture of amines and the carbonyl compounds in organic solvents under azeotropic conditions in order to remove the water formed. 2 In recent years, environmentally benign synthetic methods have received considerable anention and some solvent-free pmtucob; have been developed.J Varma, Dahiya and Kumar' reported the clay-catalyzed synthesis of imincs and cnamincs under solvent-free conditions using microwave irradiation. We report here the condensation reaction of salicylaldehyde (Ia), o-hydroxyacetophenone (lg). p-tolualdehyde (lk) anisaldehyde (lo), pochloroacetophenone (l s). 2-hydroxy-4-bromoacetophenone (lt) and p( dimethylamino)acetophenone (lu) with diumines 2 in aqueous medium without catalyst to give imines 3a-u in good to excellent yields in a very short time.S