Nitrogen-Enriched Graphene Metal and Metal Oxide Nanoparticles as Innovative Catalysts: New Uses

A new class of catalysts has recently brought the attention of researchers, which is generated by pyrolyzing first transition row metal complexes with nitrogen ligands adsorbed on an inert support, such as carbon, silica. The catalysts have a metal/metal oxide core, surrounded by a few nitrogen-enriched graphene layers (NGr). These materials, which only contain cheap and abundant metals such as iron and cobalt, catalyze reactions for which noble metals are usually required; thus representing a cheaper and more sustainable alternative of the costly noble metals. Until now, such catalysts have been employed mainly in the context of hydrogenation reactions. The objective of this work is to expand the field of applicability of this new class of catalysts. We have used Fe2O3/NGr@C to catalyze olefin cyclopropanation, a reaction for which the use of these catalysts has not previously been investigated. The activity of Fe2O3/NGr@C has been studied by using ethyl diazoacetate and α-methylstyrene as substrates. Various parameters such as solvents, temperature and time were changed. Fe2O3/NGr@C-catalysts showed best activity in dimethoxyethane at 60 oC, affording high yields of the desired cyclopropanes (mixture of cis and trans isomers) and only 1-2 % of ethyl maleate and fumarate.