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Raney nickel

Raney nickel
Light-gray powder on a glass dish
Dry activated Raney nickel
Identifiers
7440-02-0
Properties
Appearance Light-gray powder
Hazards
GHS pictograms GHS-pictogram-flamme.svgGHS-pictogram-exclam.svgGHS-pictogram-silhouette.svg
H250, H317, H351, H372, H412
P210, P273, P280, P302
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
NFPA 704
"fire diamond"
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond

Raney nickel /ˈreɪniː ˈnɪkəl/, also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel-aluminium alloy. A variety of grades are known, but most are gray solids. Some are pyrophoric, most are used as air-stable slurries. Raney nickel is used as a reagent and as a catalyst in organic chemistry. It was developed in 1926 by American engineer Murray Raney for the hydrogenation of vegetable oils.

Since Raney is a registered trademark of W. R. Grace and Company, only those products by its Grace Division are properly called "Raney nickel". The more generic terms "skeletal catalyst" or "sponge-metal catalyst" may be used to refer to catalysts with physical and chemical properties similar to those of Raney nickel. However, since the Grace company itself does not use any generic names for the catalysts it is supplying, "Raney" may become generic under US trademark law.

The Ni–Al alloy is prepared by dissolving nickel in molten aluminium followed by cooling ("quenching"). Depending on the Ni:Al ratio, quenching produces a number of different phases. During the quenching procedure, small amounts of a third metal, such as zinc or chromium, are added to enhance the activity of the resulting catalyst. This third metal is called a "promoter". The promoter changes the mixture from a binary alloy to a ternary alloy, which can lead to different quenching and leaching properties during activation.

In the activation process, the alloy, usually as a fine powder, is treated with a concentrated solution of sodium hydroxide. The simplified leaching reaction is given by the following chemical equation:


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