Amines - Nitriles (A-Level Chemistry)



A nitrile is an organic compound consisting of an alkyl group with a cyanide group (-CN) attached.

The cyanide group consists of a carbon and a nitrogen atoms linked by a triple covalent bond.

The lone pair of electrons on the N atom in the cyanide groups gives nitriles nucleophilic properties.

Nitrile Reactivity

Amine Formation

Aliphatic amines can be synthesised by the reduction of nitriles.

Nitriles can be reduced in three ways:

  • Using LiAlHâ‚„ – LiAlHâ‚„ is a strong reducing agent. First, LiAlHâ‚„ is added to a nitrile in dry ether or another non-aquous solvent. Some dilute acid is then added. The nitrile get reduced into a primary amine.
  • Using sodium metal – Nitriles can also be reduced to form a primary amine by reacting with sodium metal and ethanol.
  • Catalytic Hydrogenation – Nitriles can also be reduced to primary amines by reacting them with hydrogen gas in the presence of a metal catalyst such as nickel or platinum. High temperatures and pressures are needed.

Due to the high cost of LiAlHâ‚„, catalytic hydrogenation is the preferred method in industry

Carboxylic Acid Formation

Carboxylic acids can be formed by hydrolysis of nitriles.

The nitrile is made to react with hydrochloric acid under reflux to form a carboxylic acid and ammonium chloride salt.

The carboxylic acid can then be distilled off.

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