Urushibara nickel preparation

X-ray photoelectron (XPS) studies of nickel boride, nickel phosphide, Raney nickel and Urushibara nickel showed that the electron density on the nickel was a function of the other metal present in these catalysts. 28J29 Boron, aluminum (Raney nickel) and zinc (Urushibara nickel) all increased the electron density on the nickel while phosphorous was an electron acceptor. Comparing the electron densities on the nickel in these catalysts with that on a nickel black prepared by the thermal decomposition of nickel formate (D-Ni) gave the series Ni-B > Ni-Al > Ni-Zn > D-Ni > Ni-P. 

Selective hydrogenations, Japanese chemists have prepared (3) by hydrogenation with Urushibara nickel A catalyst of either (1) or (2). ... 

Urushibara Ni A (U-Ni-A) 6 The solids prepared by the reaction of zinc dust with aqueous nickel chloride solution, in the same way as described above, are transferred into 160 ml of 13% acetic acid and digested at 40°C until the evolution of hydrogen gas subsides or the solution becomes pale green. The catalyst can be washed with water on a glass filter under gentle suction with care to prevent the catalyst from contacting air, and then with the solvent for hydrogenation. 

Besides Urushibara Ni and Ni boride catalysts, various finely divided nickel particles have been prepared by reaction of nickel salts with other reducing agents, such as sodium phosphinate 20,85 alkali metal/liquid NH3 21 NaH-f-AmOH (designated Nic) 22,86Na, Mg, and Zn in THF or Mg in EtOH 24 or C8K(potassium graphite)/THF-HMPTA (designated Ni-Grl) 23,87 Some of these have been reported to compare with Raney Ni or Ni borides in their activity and/or selectivity. 

Urushibara Co catalysts can be prepared exactly in the same way as the corresponding Ni catalysts, using cobalt chloride hexahydrate instead of nickel chloride hexahydrate as starting material. Similarly as with Raney catalysts, Urushibara Co has been found to be more effective and selective than Urushibara Ni in the hydrogenation of nitriles, affording high yields of primary amines.105,106... 

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