Raneynikkeliä

Raneynikkeliä, often referred to as Raney nickel, is a catalyst used in organic chemistry. It is a finely divided, greyish-black powder composed primarily of nickel. The catalyst is prepared by alloying nickel with aluminum, typically in a ratio of about 50:50 by weight, and then treating the alloy with a concentrated solution of sodium hydroxide. This process leaches out most of the aluminum, leaving behind a porous structure rich in nickel. The high surface area of this porous structure is responsible for its catalytic activity.

Raney nickel is most commonly employed as a reducing agent, particularly for the hydrogenation of organic compounds. It is highly effective in cleaving double and triple bonds, converting alkenes to alkanes and alkynes to alkanes. It can also be used to reduce nitro groups to amino groups, nitrile groups to amines, and carbonyl groups to alcohols. The reaction is typically carried out in a suitable solvent, such as ethanol or water, under a hydrogen atmosphere, often at elevated pressure and temperature.

The preparation of Raney nickel requires careful handling due to its pyrophoric nature; it can spontaneously ignite in air, especially when dry. Therefore, it is usually stored and handled under water or an inert solvent. Despite this hazard, its effectiveness and relatively low cost make it a widely used catalyst in industrial and laboratory settings for a variety of organic synthesis applications.