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how aniline is manuafactured?

Aniline is the most important aromatic  amine .In laboratory ,it is prepared by the reduction of nitrobenzene with tin and HCl .

 C₆H₅NO₂           +6 [H]   Sn/HCl  _>      C₆H₅ NH₂     +  2H₂O

nitro benzene                                       aniline 

  A mixture of nitrobenzene (10 g)  and granulated tin (20 g)   is refluxed  in a round bottom flask with the simultaneous addition of 50 mL concentrated hydrochloricacid in smaller amounts (4-5 mL ) . The temperature being maintained between 360-365 K .The contents of the flask are then heated on water bath till the oil drops of nitrobenzene disappear .

On cooling the flask,a solid mass having the composition (C₆H₅NH₂HCl)₂.SnCl₄ separates out .Solid mass is then treated with calculated quantity of caustic soda .The liberated aniline floats over as a dark brown oil .Aniline is recovered from this mixture by steam distillation .                                  

The reactions involved are ,

 Sn            + 4HCl            ___________> SnCl₄             +4H

 C₆H₅NO₂  +  6 [H]              __________>   C₆H₅NH₂   +2H₂O

 2 C₆H₅NH₂   + 2HCl +SnCl₄   __________> (C₆H₅NH₂HCl)₂.SnCl₄

  aniline                                                      solid mass   

 (C₆H₅NH₂HCl)₂.SnCl₄   +8NaOH  __________> 2 C₆H₅NH₂   +  Na₂SnO₃  +6NaCl  +5H₂O

    solid mass                                                    oil layer             soluble

                                                                        (aniline)