P-1 nickel

In aqueous medium, the reduction of nickel(II) acetate with NaBFLt produces nickel boride66. This fine black precipitate, designated P-1 nickel, is a more active catalyst than Raney nickel for double-bond hydrogenations. The P-1 nickel catalyst produces less double-bond migration than standard Raney nickel, it is not pyrophoric and is more readily prepared than Raney nickel. 

P-1 nickel can also be used for the selective hydrogenation of dienes. For instance, 4-vinylcyclohexene was hydrogenated with high selectivity (98%) to 4-ethylcyclohexene (equation 18), whilst 2-methyl-1-hexene was obtained with 93% selectivity from 2-methyl-1,5-hexadiene over it (equation 19)66. 

Isolated double bonds in alkenes and cycloalkenes are best reduced by catalytic hydrogenation. Addition of hydrogen is very easy and takes place at room temperature and atmospheric pressure over almost any noble metal catalyst, over Raney nickel, and over nickel catalysts prepared in special ways such as P-1 nickel [13] or complex catalysts, referred to as Nic [49]. 

The monosubstituted double bond in 4-vinylcyclohexene is hydrogenated over P-1 nickel in preference to the disubstituted double bond in the ring, giving 98% of 4-ethylcyclohexane [73]. Similarly in limonene the double bond in the side chain is reduced while the double bond in the ring is left intact if the compound is treated with hydrogen over 5% platinum on carbon at 60° and 3.7 atm (yield 97.6%) [348]. 

Ionone-5,6-epoxide (199) undergoes acid-catalysed ring contraction and enlargement, concurrently, by [1,2] alkyl shifts, to give the isomeric cyclopentane derivative (200) and the cycloheptafuran derivative (201).71 /3-Ionone (132) can be hydrogenated selectively with P-1 nickel catalyst to give dihydro-/3-ionone (202).72... 

The more ethanol in the reduction solvent, the greater the amount of BOj found in the resulting nickel boride precipitate.This ion is formed by the hydrolysis of borohydride but, since it is not very soluble in ethanol, it is not kept in solution in alcoholic solvents. The BO2 is apparently responsible for the decreased activity and increased selectivity of the P-2 nickel boride. 3,35 Vvt]ien the P-2 catalyst was isolated and washed with water before use, the resulting P-2W catalyst was more active than both the P-2 and P-1 nickel borides but it became less selective in alkene hydrogenation than the P-2 catalyst. ... 

The horohydride reduction of a nickel salt solution containing small amounts of other metal salts can lead to co-reduced mixed metal borides that frequently have enhanced catalytic properties when compared to the unmodified nickel boride. The presence of about 2% chromium significantly increased the activity of a P-1 nickel boride toward aldehyde hydrogenation. Molybdenum, tungsten and vanadium modifiers were somewhat less effective than chromium while the presence of a small amount of cobalt had an inhibiting effect on the reaction.22 As the data in Fig. 12.2 show, the amount of chromium responsible for optimum P-1 nickel boride activity depends on the substrate being hydrogenated.39... 

Fig. 12.2. The promoting effect of adding chromium to the P-1 nickel boride catalyst in the hydrogenation of various substrates.

A parameter, Aq, was defined as the relative change in electron density on nickel resulting from electron transfer between nickel and the second element as compared with that on nickel black. Table 12.2 shows the Aq values for these different nickel catalysts. 29 That for the P-1 nickel boride25 is the most negative and that for the NiP-1 nickel phosphide is the most positive. In Fig. 12.5 is shown the relationship between the areal turnover frequencies for the hydrogenation of styrene over these catalysts and their Aq values. 29 These data... 

P-1 nickel can also be used for the selective hydrogenation of dienes. For instance,... 

Hydrogenation catalyst. C. A. Brown1 has compared P-1 nickel boride with W-2 Raney nickel as hydrogenation catalysts and finds that the former is somewhat more active and produces less double-bond migration. In addition it is not... 

The properties of P-1 nickel boride have also been further investigated. This hydrogenation catalyst has been fovind to be more active and to cause less migration of double bonds than Raney nickel. 

P. Goldberg, "Nickel—Zinc Cells Part 1," Proceedings of the 21 st A.nnual Power Sources Conference 1967. 

Steam forms a protective white film at temperatures up to about 250°C, but above this temperature steam can, under some conditions, react with aluminium progressively to form aluminium oxide and hydrogen. Sintered aluminium powder (S. A.P.) has relatively good resistance to steam at 500°C, but at about 300°C an addition of 1% nickel to the S.A.P. is needed to prevent rapid disintegration. 

It can also be deposited by the hydrogen reduction of the nickel chelate, Ni(C5HFg02)2 at 250°C.P 1 In addition to thermal processing reviewed above, nickel is deposited by laser C VD from the carbonyl with a krypton or a pulsed CO2 laser.P lP l... 

Iron, nickel, cobalt, molybdenum, and tungsten powders produced by the pyrolysis of the respective metal carbonyl (see Ch. 3).P 1... 

R. Karrer, P. Bochsler, C. Giammanco, F. M. Ipavich, J. A. Paquette, and P. Wurz. Nickel Isotopic Composition and Nickel/hon Ratio in the Solar Wind Results from SOHO/ CELIAS/MTOF, Space Science Reviews, 130, no. 1-4(2007) 317 -321. 

Nickel of activity comparable to Raney nickel is obtained by reduction of nickel salts, e.g. nickel acetate, with 2 mol of sodium borohydride in an aqueous solution and by washing the precipitate with ethanol [13, 47] Procedure 7, p. 205). Such preparations are designated P-1 or P-2 and can be conveniently prepared in situ in a special apparatus [4] Procedure 2, p. 202). They contain a high percentage of nickel boride, are non-magnetic and non-pyrophoric and can be used for hydrogenations at room temperature and... 

The production of 1-alkenes from ethylene oligomerization was carried out with high selectivity in ionic liquids in the presence of a cationic nickel complex catalyst (ri -methallyl)-[bis(diphenylphosphino)methane-monoxide-K -P,0]nickel(II) hexafluoroantimonate, [(mall)-Ni(dppmo)]Sbp6 (240). The overall reaction rate of... 

In the presence of PhBr and PhCH2Br, both Ni(BF4)2(bipy)3 and NiCl2(bipy) showed classical catalytic behavior. A peak for the product of the first oxidative addition of the reduced nickel complex appeared at p = —1.4 to —1.5V when the reactant was Ar(Ni)Br. In this case, the electrochemical catalysis was carried out by maintaining the potential of the working electrode at E" = —1.4 V vs. silver. 

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