INFLUENCE OF THE STARTING NI-AL PHASES ON THE ENANTIO-DIFFERENTIATINGPROPERTIES OF TARTARIC ACID-MODIFIED RANEY-NICKEL

Using well-defined pure phases: Al3Ni2, Al3Ni and the Al/AI(3)Ni eutec tic we prepared tartaric acid-modified Raney nickel (RNi(3-2), RNi(3-1 ), RNiE). Their catalytic properties were investigated, in the hydroge nation 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 h as 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%.