Beneficial effect of water as second solvent in ionic liquid biphasic catalytic hydrogenations

When reactions take place in ionic liquids, a solvent is normally used to extract the products after reaction. It is reported here how the presence of the solvent during the reaction already can seriously improve the catalytic performance. Above all, employing water as the added solvent enhanced the catalytic activities significantly, ascribed to the creation of a well mixed ‘emulsion-like’ system. The reductions of methyl 2-acetamidoacrylate with Rh–EtDuPHOS and of 2-cyclohexen-1-one with Wilkinson’s catalyst in bmimPF6 were thus successfully performed in the presence of water. The complexes were easily recycled and Rh–EtDuPHOS was even no longer air sensitive.