Copper nanoparticles loaded polymer vesicles as environmentally amicable nanoreactors: A sustainable approach for cascading synthesis of benzimidazole

Abstract

This paper reports the synthesis and characterization of Cu nanoparticle loaded, surfactant free metallovesicles (CuNPs@vesicles) as nanoreactors to produce benzimidazoles via cascade reaction. The vesicles exhibited uniform size distribution, spherical morphology, excellent stability and efficient Cu loading. This strategy is unique for the fact that, environmental contaminants like nitroaniline have been utilized as precursor and converted into fine chemicals of commercial significance via non-toxic intermediates. CuNPs@vesicles reduces 2-nitroaniline to o-phenylenediamine which further acts as precursor for benzimidazole synthesis. Thus the reaction occurs via two step cascade pathway comprising reduction and CN cross coupling reactions in water. The preliminary studies suggest encouraging results for performing dehydrogenative coupling under relatively mild conditions using CuNPs@vesicles as a catalyst. All the products are obtained in good to excellent yield with facile catalyst regeneration and recyclability upto 5 cascading cycles.