The Amines and Amides

The Amines

  • The Amines are the organic chemistry relatives of ammonia:
  • However, in amines, one or more of the hydrogen atoms on the ammonia molecule are replaced by alkyl chains:
  • The alkyl groups on the amines do not have to be the same.
  • Amines with one alkyl group are primary amines, with two they are secondary, and with three they are tertiary amines.
  • The amines are named following the general rules. The alkyl groups are arranged in alphabetical order, and placed in front of the suffix amine.
  • Sometimes the amines can be named using “amino” to represent a NH2 group, for example 2-amino-pentane:

Physical Characteristics

  • The amines with low molecular masses are gases, or volatile liquids. The volatile amines resemble ammonia in having strong “fishy smells”.

The lone pair of electrons on the nitrogen atom.

  • The lone pair of electrons on the nitrogen atom is responsible for many of the amines characteristics.
  • The lone pair is similarly found in ammonia; the reactions of the amines closely resemble the reactions involving ammonia.


  • Amines with small alkyl groups are very soluble in water. This is because hydrogen bonding occurs between the amine and water molecules:
  • The larger the alkyl chain and the more of them there are, the less soluble the amine is in water.

Amines as Bases

  • The lone pair of electrons on the nitrogen atom can take part in dative bonding.
  • The electron pair can be donated to an H+ ion; the amine can act as an H+ acceptor, and thus can act as a base. For example:
  • Like ammonia, amines dissolve in water to form an alkaline solution. This is due to the formation of hydroxide ions:


  • Ammonia can react with an acid chloride to produce a primary amide containing the CONH2 group:
  • The amines can also react in the same way; however a secondary amide is produced:

Amines as Nucleophiles

  • Nucleophiles are substances that can “attack” a positively charged carbon atom by donating a pair of electrons.
  • The lone pair on the nitrogen atom allows ammonia to act as a nucleophile:

    CH3CH2Br(aq) + NH3(aq) CH3CH2NH3+(aq)+ Br-(aq) CH3CH2NH2(aq) + H+ + Br-(aq)

  • As the amines have a lone pair of electrons, they can also act as nucleophiles:

The Amides

  • Amides are derived from carboxylic acid.
  • The hydroxyl group on the carboxylic acid is replaced by an NH2 group.
  • The C-N bond can be broken by hydrolysis to produce a carboxylic acid. The amides need to be heated under reflux with either an acid or alkali catalyst for the reaction to occur:
  • When the amide is hydrolysed using an acid, the NH3 molecule produced acts as a base and accepts a proton from the acid, thus becoming NH4+.
  • When it is hydrolysed using an alkali, the carboxylic acid donates a proton to the alkali, changing the carboxyl group into a COO- group

Useful books for revision

Revise A2 Chemistry for Salters (OCR A Level Chemistry B)
Salters (OCR) Revise A2 Chemistry