34.2.1—Preparation of phenylamine via the nitration

Benzene is first nitrated to nitrobenzene. Hot tin and concentrated hydrochloric acid reduce the nitro group to an ammonium salt; aqueous sodium hydroxide then liberates phenylamine.

Treat it as a three-stage route: electrophilic substitution, reduction in acid, then basification. Separating the stages prevents the acid–base work-up from being missed.

C₆H₆ → C₆H₅NO₂ → C₆H₅NH₃⁺Cl⁻ → C₆H₅NH₂. NaOH converts the ammonium salt to the free amine.

The reduction product in the acidic mixture is not immediately free phenylamine; it is protonated until alkali is added.