A solution of
380 g. of sodium hydroxide in 1.5 l. of distilled water, contained in a
4-l. beaker (Note
1) equipped with an
efficient stirrer (Note
2), is cooled in an
ice bath to 10°, and
300 g. of nickel-aluminum alloy (Note
3) is added to the solution in small portions, with stirring, at such a rate that the temperature does not rise above 25° (Note
4), the beaker being allowed to remain in the ice bath. When all the alloy has been added (about 2 hours is required) the stirrer is stopped, the beaker is removed from the ice bath, and the contents are allowed to come to room temperature. After the evolution of
hydrogen becomes slow, the reaction mixture is allowed to stand on a
steam bath until the evolution of
hydrogen again becomes slow (about 8–12 hours). The heating should not be too rapid at the beginning or the solution may foam over. During this time the volume of the solution is maintained constant by adding distilled water if necessary. After heating, the
nickel is allowed to settle and most of the liquid is decanted. Distilled water is then added to bring the solution to the original volume; the
nickel is suspended by stirring, again allowed to settle, and the solution is decanted. The
nickel is then transferred to a
2-l. beaker (Note
5) with the aid of distilled water, and the water is again decanted. A solution of
50 g. of sodium hydroxide in 500 ml. of distilled water is added; the catalyst is suspended and allowed to settle; and the alkali is decanted. The
nickel is washed by suspension in distilled water and decantation until the washings are neutral to litmus and then ten times more to remove the alkali completely (twenty to forty washings are required) (Note
6). The washing process is repeated three times with
200 ml. of 95% ethanol and three times with absolute
ethanol; the catalyst is then stored under absolute
ethanol in bottles which are completely filled with absolute
ethanol and tightly closed (Note
7). The product is highly pyrophoric and must be kept under a liquid at all times. The
Raney nickel contained in the suspension weighs about
150 g. (Note
8).
To prepare the catalyst under
methylcyclohexane (Note
9), the catalyst, which has been prepared as above and washed free of alkali with water, but to which no
ethanol has been added, is covered with
1 l. of methylcyclohexane which is distilled from an
oil bath until all the water has been codistilled with the hydrocarbon, more of the
methylcyclohexane being added from time to time so that the
nickel always remains covered. When the catalyst is free from water it becomes freely suspended in the liquid.