Influence of the starting Ni-Al phases on the enantio-differentiating properties of tartaric acid-modified Raney nickel

Using well-defined pure phases: Al3Ni2, Al3Ni and the Al/AI(3)Ni eutectic we prepared tartaric acid-modified Raney nickel (RNi(3-2), RNi(3-1), RNiE). Their catalytic properties were investigated, in the hydrogenation of methyl acetoacetate at constant hydrogen pressure (1.1 MPa) and temperature (333 K) in ethyl acetate. The enantiomeric excess went from 16% on RNi(3-2) to 25% on RNi(3-1) and up to 45% on RNiE which has been prepared using an aluminium in a high state of purity. In the presence of sodium bromide in the modifying solution, RNiE remains the best catalyst: with an ee of 80%.