6.2.1

• Basicity and Preparation of Amines

  Amines are produced when one or more of the hydrogen atoms in ammonia are replaced with an alkyl group. They can be classified as primary, secondary or tertiary amines, depending on how many alkyl groups are bonded to the nitrogen atom.
• Amines react with water to form an alkaline solution

  • The lone pair of electrons on the amine’s nitrogen atom can accept a hydrogen from a water molecule, therefore acting as a base

  →This releases OH- ions into the solution

  To Produce Salts Amines react with acids to form an ammonium salt

  • Again, the amine acts as a base and accepts a proton to form a quaternary ammonium salt
• Basicity and Preparation of Amines

  Amines are produced when one or more of the hydrogen atoms in ammonia are replaced with an alkyl group. They can be classified as primary, secondary or tertiary amines, depending on how many alkyl groups are bonded to the nitrogen atom.

  
• Preparation of Aliphatic Amines

  Nucleophilic Substitution Aliphatic amines can be produced from the nucleophilic substitution reaction between a halogenoalkane and ammonia in a sealed tube

  • One mole of halogenoalkane reacts with two moles of ammonia, producing a primary amine and an ammonium salt (ammonium ion bonded to a halide ion).

  Example: Nucleophilic substitution of bromoethane with ammonia

  • This substitution reaction can continue until all the hydrogen atoms have been replaced with amine groups + an additional substitution can occur, producing a quaternary ammonium salt
• Reduction of Nitriles

  Aliphatic amines can also be produced by the reduction of nitriles by hydrogenation

  • This reduction requires a combination of hydrogen with a nickel catalyst (catalytic hydrogenation)
• Preparation of Aromatic Amines Aromatic amines can be produced from the reduction of nitrobenzene using concentrated hydrochloric acid (HCl) and a tin catalyst

  • Aromatic amines consist of an amine group and a benzene ring