Prepare 4-bromoaniline from aniline | p-bromoaniline synthesis

4-bromoaniline can be prepared by aniline easily. Aniline is an ortho para activator. In 4-bromoaniline bromine atom exist in para position related to the amine group.

With liquid bromine

But reaction of aniline and bromine liquid will give 2,4,6-tribromoaniline. Therefore we have to control the reaction if we need to prepare 4-bromoaniline.

Question: Derive 4-bromoaniline from benzene

4-bromoaniline / p-bromoaniline

4-bromoaniline , p-bromoaniline

Solution

Aniline is a ortho para activator. When liquid bromine (Br2(l)) is added to the aniline, it gives 2,4,6-bromoaniline.

aniline and liquid bromine reaction

But we need only one bromine atom to connect to the para position of aniline. Therefore we reduce the activity of aniline by the reaction of aniline and ethanoyl chloride (CH3COCl). Then we add Br2(l) to thenewly formed compound.



Aniline and ethanoyl chloride reaction

Aniline is a strong ortho para activator. Aniline and ethanoyl chloride react to give N-phenylethanamide which is a ortho para Moderate activator. This product is an amide compound.

-NH-CO-CH3 group results a steric impediment around that group. Therefore, substitutions to ortho places is more difficult than para places.

Aniline and ethanoyl chloride reaction

N-phenylethanamide and liquid bromine reaction

Two products are given. Due to steric impediment, bromine is substituted more to para position. Therefore major product is para substituted compound.

N-phenylethanamide and liquid Br2 reaction


Conversion of benzene to 4-bromoaniline

benzene to 4-bromoaniline

Prepare 2,4,6-tribromoaniline from aniline

Reaction between aniline and liquid bromium will give 2,4,6-tribromoaniline. 2,4,6-tribromoaniline is a white precipitate.

Prepare 2,4,6-tribromoaniline


m-bromoaniline can be prepared by aniline?

We cannot prepare m-bromoaniline in one step from aniline because aniline is a ortho - para activator. In m-bromoaniline, bromine atom is attached to the meta position of aniline. We have to convert aniline to a deactivater and then attach bromine atom to the meta position.



What are the other names of 4-bromoaniline

p-bromoaniline | para-bromoaniline



How many steps are required to preparation of 4-bromoaniline from aniline ?

There are three steps in preparation of 4-bromoaniline from aniline.

  1. Reducing activity of aniline
  2. Substitution of bromine
  3. Recovery of aniline


How is phenyl amine converted into 4-bromoaniline

Phenyl amine is aniline. The conversion of aniline to 4-bromoaniline is explained above.