Reduction of Nitriles to Amines

Nitriles contain the −C≡N group. Because a nitrile can be made from a haloalkane (adding one carbon atom to the chain), it is a useful intermediate: the nitrile group can then be converted into other functional groups.Reduction of a nitrile forms a primary amine. The C≡N triple bond gains hydrogen and becomes a −CH₂NH₂ group. OCR uses hydrogen gas with a nickel catalyst (H₂/Ni) for this reduction.In a general equation, 4 hydrogen atoms (2 H₂) are added:R−C≡N + 2H₂ → R−CH₂NH₂Worked example: propanenitrile, CH₃CH₂CN, is reduced with H₂/Ni.CH₃CH₂CN + 2H₂ → CH₃CH₂CH₂NH₂The product is propylamine (propan-1-amine). Notice that the carbon atom of the nitrile group stays in the chain, so the amine has the same number of carbon atoms as the nitrile.Combining the two steps gives a route from a haloalkane to an amine with one extra carbon: bromoethane (2 carbons) → propanenitrile → propylamine (3 carbons). This is different from reacting a haloalkane directly with ammonia, which keeps the same number of carbon atoms.The amine is basic because the lone pair on its nitrogen atom can accept a proton.