Ruthenium hydroxide on magnetite as a magnetically separable heterogeneous catalyst for liquid-phase oxidation and reduction

Abstract

Three kinds of reactions, (i) aerobic oxidation of alcohols, (ii) aerobic oxidation of amines, and (iii) reduction of carbonyl compounds to alcohols using 2-propanol as a hydrogen donor, could efficiently be promoted by an easily prepared ruthenium hydroxide catalyst on magnetite (Ru(OH)_x/Fe₃O₄). A wide variety of substrates including aromatic, aliphatic, and heterocyclic ones could be converted to the desired products in high to excellent yields without any additives such as bases and electron transfer mediators. After the reaction, the catalyst/product(s) separation could be easily achieved with a permanent magnet and more than 99% of Ru(OH)_x/Fe₃O₄ catalyst could usually be recovered for each reaction. The catalysis for these reactions was intrinsically heterogeneous, and Ru(OH)_x/Fe₃O₄ recovered after these reactions could be reused without appreciable loss of the catalytic performance.