Synthesis of imines, diimines and macrocyclic diimines as possible ligands, in aqueous solution

Abstract

Although it is recognized that the presence of water is disadvantageous for imine synthesis, we demonstrate that such synthesis can be effective in completely aqueous media, without any catalyst and under mild conditions. Thus, aryl-aryl, aryl-alkyl, alkyl-aryl and alkyl-alkyl monoimines as well as a large variety of diimines are obtained by direct condensation of the corresponding carbonyl compounds and amines, in water. The same process is used to synthesize macrocyclic diimines starting from methylene, ethylene, trimethylene and tetramethylene glycol bis(2-formylphenyl ether) and ethylene-, trimethylene- and tetramethylene-diamine, some of these macrocycles being known for their chelating properties.