CHITOSAN-SUPPORTED MERCURY(II) ACETATE AS A CATALYST FOR TRANSVINYLATION REACTIONS OF AZOLES

Abstract

The application of homogeneous catalysts - transition metal complexes - on organic polymers is of a great interest among researchers. Heterogeneous catalysts often have a long life span and are easy to separate from the reactants and reaction products, and they can also be reused. A homogeneous catalyst on a heterogeneous support acts as if it were in solution, but simultaneously it is a separate stationary phase. In this study we tried to use chitosan as a carrier for metal ions (particularly mercury(II), knowing in advance that chitosan is a good ligand for transition metals). Interest in chitosan is associated with their unique physiological and environmental properties, such as biocompatibility, biodegradation, and chelating ability. Here, an efficient and easy method of vinylation of azoles in the presence of chitosan-supported mercury(II) acetate heterogenous catalytic system is reported. As a result, several products were synthesized in high yields. The developed procedure is easy to perform, requires less amount of catalyst, shortens reaction time, excludes the formation of side products, and provides higher selective yields of vinylated products, reduces water contamination with mercury salts. Furthermore, it is possible to recover the catalyst from the reaction mixture and recycle this catalytic system more than four times.