Question

Convert : Aniline into 1, 3, 5- tribromo benzene.

Answer 1

Hint: The reaction of aniline to 1, 3, 5- tribromo benzene is an electrophilic substitution reaction in which bromo groups are substituted on a benzene ring and an amino group is removed by forming diazonium salt. First, the bromination occurs resulting in formation of 1, 3, 5- tribromo aniline and then the amino group is removed to give the product 1, 3, 5- tribromo benzene.

Complete step by step answer:
The aniline is a benzene ring having a -$N{H_2}$ group attached to it. The benzene is an aromatic compound. It is stabilised because of resonance. It does not undergo addition reactions because if it does, then the resonance of the ring is disturbed and it gets destabilised. Thus, it undergoes electrophilic substitution reaction. The reaction of aniline to 1, 3, 5- tribromo benzene is an electrophilic substitution reaction in which bromo groups are substituted on a benzene ring. The electrophile is $Br \oplus $ ion. The reaction takes place as- First, the bromine water reacts with aniline to give 1, 3, 5- tribromo aniline. Then, this product reacts with sodium nitrate and HCl to give diazonium salt. This reduction gives 1, 3, 5- tribromo benzene. The reaction can be drawn as -

Note: The -$N{H_2}$ group is ortho para directing in nature. It directs the incoming groups to ortho and para positions of the benzene ring. So, it is not removed first. If it is removed first, the incoming group would attack at first carbon and the next two bromide ions will get substituted according to the first bromide ion.