Raney nickel: Encyclopedia II - Raney nickel - Applications

Raney nickel - Applications

Raney nickel is used in a large number of industrial processes and in organic synthesis because of its stability and high catalytic activity at room temperature.^[2][4] It is typically used in the reduction of compounds that have multiple bonds, such as alkynes, alkenes^[5], nitriles^[6], dienes, aromatics^[7] and carbonyls. Additionally, Raney nickel will reduce heteroatom-heteroatom bonds such as nitro groups, and nitrosamines^[8]. It has also found use in the reductive alkylation of amines^[9] and the amination of alcohols.

A practical example of the use of Raney nickel in industry is shown in the following reaction, where benzene is reduced to cyclohexane. Reduction of the aromatic structure of the benzene ring is very hard to achieve through other chemical means, but can be effected by using Raney nickel. Other heterogeneous catalysts, such as those using platinum group elements, may be used instead to similar effect, but these tend to be more expensive to produce than Raney nickel. After this reaction cyclohexane may be used in the synthesis of adipic acid, a raw material used in the industrial production of polyamides such as nylon.^[10]

When reducing a carbon-carbon double bond, Raney nickel will add hydrogen in a syn fashion.^[10]

In addition to being a catalyst, Raney nickel will also act as a reagent to desulfurize organic compounds.^[11] For example, thioacetals will be reduced to hydrocarbons:^[10]

Nickel sulfide will precipitate as millerite, while ethane can be easily separated through distillation. Similar tranformations are the Clemmensen reduction and the Wolff-Kishner reduction.

Adapted from the Wikipedia article "Applications", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki