An effect of modification conditions of powdered nickel-cobalt catalysts on enantioselectivity of hydrogenation of ethyl acetoacetate has been studied. Addition of NaBr to the modifying solution of RR-(+)-tartaric acid does not improve enantioselectivity of the catalyst. When the Ni-Co catalysts are modified with amino acids, the best results are obtained with L-β-phenylalanine (17% ee).

The surface cobalt concentration in the powder bimetallic Ni-Co catalysts (ratio Co/Ni ≈ 0.25) was shown by X-ray photoelectron spectroscopy to be 2–4 times that of the volume content. Both Ni and Co exist in mixed valent states, viz. , M 0 and M 2+ , even after catalyst reduction. After ethyl acetoacetate hydrogenation, the cobalt content on the surface increases 16 times compared to that in the bulk. In addition, the metals are partially oxidized, and the amount of Ni 0 and Co 0 in the surface layers of the catalyst decreases 2–3 times. It was assumed that the increase in the cobalt content indicates an increase in the amount of cobalt complexes that involve the modifier, substrate, and reaction product, and which shield the nickel active sites. As a result, the enantioface differentiating ability of the catalyst decreases.

The influence of the metal content on the support, the conditions of the preparation of the catalysts, and the reaction conditions on the enantioselectivity of the liquid-phase hydrogenation reaction of ethyl acetoacetate in the presence of Ni and Ni-Co catalysts supported on Al2O3 and SiO2, and modified by RR(+)-tartaric acid, was investigated. The maximal optical yield (66–76%) was obtained for the 20% Ni/Al2O3 catalyst.