Raney nickel
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Raney nickel, sometimes also called spongy nickel, is a fine-grained solid composed mostly of a nickel-aluminium alloy.
Contents
Composition
The most common composition for this alloy is 1:1 Ni/Al, though 21:29 Ni/Al and 3:7 Ni/Al are also known.
Properties
Raney nickel is a dull gray powder. Very fine Raney nickel is known to be pyrophoric.
Raney nickel is commonly used in hydrogenation reactions, in various chemical reductions.
This is done by mixing Raney nickel with a concentrated solution of sodium hydroxide.
Availability
Raneu nickel is sold by various chemical suppliers.
Preparation
Raney nickel can be prepared by dissolving nickel in molten aluminium, followed by cooling ("quenching"). Depending on the Ni:Al ratio, quenching produces a number of different phases. Sometimes, a third metal, such as zinc or chromium is added in small amounts to enhance the activity of the resulting alloy ("promoter"). The resulting alloy is grounded in a ball mill or some other mill to a very fine powder.
Projects
- Hydrogenation of organic compounds
- Make cyclohexane from benzene
- Make sugar alcohols from various sugar (ex: sorbitol from sucrose)
- Desulfurization
Handling
Safety
Raney nickel is harmful if ingested due to its nickel. Dry and finely powdered Raney nickel is pyrophoric. Work should be done under inert atmosphere.
Storage
Raney nickel should be kept in closed containers, preferably metal coated in anti-static coating. Another common form is storage underwater.
Disposal
Raney nickel should be dissolved with a strong acid to nickel salts which can either be recycled or taken to hazardous waste disposal facilities.
