Preparation variables for new nickel catalysts modified with tartaric acid

Preparation variables for new nickel catalysts modified with tartaric acid 

The important question of the effect of the composition of the original Ni-Al alloys on enantioselective ability was not studied in detail. But Zubareva et al. studied samples of Ni catalysts prepared from commercially available Ni-Al alloys with different contents of intermetallic NiAls and Ni2Als with results shown in Table 4.2. An increase of NiAls in the alloy facilitated etching of the alloy and diminished the contents of Al in the resulting Ni catalysts. 

RNi No. 3, prepared from the commercial NiAl alloy No. 3, containing 2% Cr-i-Ti and small amounts of other additives, contained 6.8% Al, approximately half of the Al in RNi sample No. 2, which was prepared from the NiAl alloy No. 2. Impurities during the preparation of RNi No. 3 were almost completely removed. Table 4.2. and Fig. 4.1. show that decreasing the NisAls phase in the alloy and increasing the contents of NiAU, promoted an increase in both the general aetivity and the enantioselectivity of the resulting RNi catalysts. 

Harada et al. have found that the presence of traces of aluminium or Al-compounds in Ni catalysts are unfavorable for enantioselective activity. Therefore the use of Ni catalyst prepared by 

It was found that the addition of 1-2% AcOH to the reaction mixture is very favorable. Table 4.3. shows that commercially available NiO reduced for 1 h at 350°C in flowing hydrogen gives the best results (81.6% ee) in the hydrogenation of MAA. 

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