Benzene to Aniline | Nitrobenzene Reduction
We can prepare aniline from benzene from two steps. First, we prepare nitrobenzene from benzene and then aniline is prepared by nitrobenzene.
Two steps of benzene to aniline
- Benzene to nitrobenzene
- Nitrobenzene to aniline
Prepare nitrobenzene from benzene
Concentrated nitric acid and sulfuric acid acids are heated around 400C with benzene. Nitrobenzene is given as the product.
Nitrobenzene to aniline | Nitrobenzene reduction
Nitrobenzene is reduced to aniline by Sn and concentrated HCl. Instead of Sn, Zn or Fe also can be used. Aniline salt is given from this reaction. Then aqueous NaOH is added to the aniline salt to get released aniline.
Aniline salt
Aniline salt has weak acidic characteristics. Therefore it reacts with strong alkalis such as NaOH, KOH and release aniline.
Reaction mechanisms
- Reaction of benzene with concentrated H2SO4 and HNO3 at 400C is a electrophilic substitution reaction.
- Nitrobenzene reduction to aniline is a redox reaction. It give the aniline salt.
- Aniline salt and dilute aqueous NaOH reaction is an acid base reaction.
How do you identify aniline and benzene?
Benzene is a clear, colorless, highly flammable and volatile, liquid compound. Aniline is a yellowish to brownish oily liquid with a musty fishy odor organic compound.
testing with liquid bromine
With liquid bromine, aniline gives a white precipitate which is 2,4,6-tribromoaniline. When aniline reacts with liquid bromine, brown colour of liquid bromine is reduced. But benzene does not react with liquid bromine.
We know, aniline is strong activator. Therefore aniline's ability to do an electrophilic substitution reaction is greater than benzene. Hence aniline readily reacts with liquid bromine.