Laboratory preparation of aniline

Aniline was first prepared by Unverdorben (1826) by dry distillation of indigo. In the laboratory, it can be prepared by the reduction of nitrobenzene with tin and hydrochloric acid.

Sn,HCl
C6H5NO2 + 6H ——————→ C6H5NH2 + 2H2O

Aniline produced combines with H2SnCl6 (SnCl4 + 2HCl) to form a double salt.

2C6H5NH2 + SnCl4 + 2HCl —→ (C6H5NH3)2 SnCl6
Double salt

From double salt, aniline is obtained by treating with conc. caustic soda solution.

(C6H5NH3)2SnCl6 + 8NaOH —→ 2C6H5NH2 + 6NaCl + Na2SnO3 + 5H2O

On a commercial scale, aniline is obtained by reducing nitrobenzene with iron filings and hydrochloric acid.

Aniline.JPG

Aniline is also obtained on a large scale by the action of amine on chlorobenzene at 200°C under 300-400 atm pressure in presence of cuprous catalyst.

200oC
2C6H5 + 2NH3 + Cu2O ———————→ 2C6H5NH2 + Cu2Cl2 + H2O

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