Selective hydrogenation

Non-toxic and non-pyrophoric copper-based catalysts prepared with a simple and reliable technique based on the electrostatic interaction of the catalyst precursor and the support can be used with excellent results in terms of activity and selectivity in the hydrogenation of several substrates useful as intermediates for the preparation of fine chemicals. The high dispersion of the supported copper phase obtained by means of the preparation method used grants an outstanding activity under very mild reaction conditions, that means 1 atm of H₂ and temperatures lower than 100 °C. Moreover the use of copper instead of traditional noble metals allows to obtain much more selective results when facing with polyfunctional molecules.

Copper catalysts supported over silica can be used for the selective hydrogenation of C=C double bonds even when other double bonds or carbonyl compounds are present in the molecule. This was found to be the case of the selective hydrogenation of 4-(6-methoxy-2-naphtyl)-3-buten-2-one to Nabumetone® (scheme 1), such as in the reduction of b-ionone into hydro-b-ionone. Cu/SiO₂ can succesfully be used also in the reduction of ketones and aldehydes, both under hydrogenation and under hydrogen transfer conditions.

Refernces:

F. Zaccheria, N. Ravasio, R. Psaro, A. Fusi, “Heterogeneous Selective Catalytic Hydrogenation of Aryl Ketones to Alcohols without Additives”, Tetrahedron Lett., 2005, 46, 3695-3697.
F. Zaccheria, N. Ravasio, M. Ercoli, P. Allegrini. “Heterogeneous Cu-catalysts for the Reductive Deoxygenation of Aromatic Ketones without additives”, Tetrahedron Lett., 2005, 46, 7743-7745.
N. Ravasio, F. Zaccheria, P. Allegrini, M. Ercoli, “Selective hydrogenation of 4-(6-methoxy-2-naphtyl)-3-buten-2-one to Nabumetone®”, Catalysis Today, 2007, 121,