• Phenylamine?is an organic compound consisting of a benzene ring and an?amine?(NH₂) functional group
• It can be produced in a?three-step synthesis?reaction followed by the separation of phenylamine from the reaction mixture
  • Step 1-?Benzene undergoes?nitration?with concentrated nitric acid (HNO₃) and concentrated sulfuric acid (H₂SO₄) at 25 to 60?^oC to form?nitrobenzene
  • Step 2 -?Nitrobenzene is?reduced?with?hot tin?(Sn) and?concentrated hydrochloric acid?(HCl)?under reflux?to form an acidic mixture that contains the organic product C₆H₅N⁺H₃
  • Step 3?- Sodium hydroxide (NaOH) is added to the acidic reaction mixture to form?phenylamine
  • Step 4 -?The phenylamine is separated from the reaction mixture by?steam distillation

The overall reaction of formation of phenylamine from benzene

Multi-step synthesis of phenylamine from benzene

• Both the benzene ring as well as the -NH₂?group in?phenylamine?can take part in chemical reactions
• These reactions include
  • The?bromination?of phenylamine
  • Formation of a?diazonium?salt

Bromination of phenylamine

• Phenylamines react in?electrophilic substitution?reactions in a similar way as?phenols
• The lone pair of electrons on the nitrogen atom in phenylamines donate electron density into the benzene ring
  • In phenols, the oxygen atom donates its lone pair of electrons instead
• The?delocalisation?of the electrons causes an?increased electron density?in the benzene ring
• The benzene ring, therefore, becomes?activated?and becomes more readily attacked by?electrophiles
• The incoming electrophiles are directed to the 2,4 and 6 positions
• Phenylamines, therefore, react under milder conditions with?aqueous bromine?at?room temperature?to form 2,4,6-tribromophenylamine

Bromination of phenylamines gives 2,4,6-tribromophenylamine

Formation of diazonium salt

• Diazonium?compounds are very reactive compounds containing an -N₂⁺?group
• The amine (-NH₂) group of phenylamines will react with?nitric(III) acid?(HNO₂) at a temperature below 10 °C to form?diazonium salts
  • Since nitric(III) acid is unstable, it has to be made in the?test-tube?by reacting sodium nitrite (NaNO₂) and?dilute acid?(such as HCl)
• These?diazonium salts?are so unstable that they will upon further warming with water to form a?phenol

Phenylamine can form an unreactive diazonium salt which thermally decomposes to a phenol