Amines

Question 1

What method is used to prepare aliphatic amines? Describe the method.

Answer 1

Nucleophilic substitution.

Warming Halogenoalkanes gently with an excess of ammonia, using ethanol as the solvent.

Question 2

What method is used to prepare aromatic amines?

Answer 2

Reduction. Nitrobenzene and other nitroarenes can be reduced using tin and conc HCl, heated under reflux, followed by neutralisation of the excess HCl. Tin and HCl act as the reducing agent [H]

Question 3

Describe the synthesis of an azodye

Answer 3

TWO STEPS

1) diazotisation: forming the diazonium ion.
- HNO2 is made by reacting sodium nitrate (NaNO2) with excess HCl
- nitrous acid then reacts with aromatic amine to form a diazonium salt

2) coupling: diazonium salt reacts with a phenol (or other aromatic compound) under alkaline conditions.

Question 4

Describe the reactions of amines with acids to form salts

Answer 4

Base + acid -> salts

Amines are bases