How can you separate a mixture of nitrobenzene and phenyl amine?

1 Answer
Jun 8, 2015

The answer is "with ease".

Because phenylamine is weakly basic, and nitrobenzene is neither acidic nor basic, repeated washing of the mixture with volumes of dilute acid (say 0.1 mol/L) will partition the base (now protonated) in the acidic aqueous phase. The combined aqueous extracts are then treated with conc. aqueous sodium hydroxide to regenerate the base. Washing this mixture with ether will partition the free base back to the organic phase.

Alternatively, the phenylamine could be isolated as its hydrochloride salt, recrystallized, and then neutralized to recover the base.