Aniline, phenylamine or aminobenzene is an organic compound with the formula C₆H₅NH₂. It is an organic chemical compound, specifically an aryl amine, consisting of a phenyl group attached to an amino group. The chemical structure of aniline is shown at the right. It is now used mainly in the manufacture of polyurethane, although it previously was mainly used more for dyes and drugs.


PRODUCTION
Aniline is produced industrially in two steps from benzene:



First, benzene is heated with a concentrated mixture of nitric acid and sulfuric acid at 50 - 60 °C, where one hydrogen atom is displaced to give nitrobenzene. In this nitration reaction, nitric acid first reacts with sulfuric acid giving the electrophile ⁺NO2 which is attracted towards the π-electron cloud of benzene. The ⁺NO2 electrophile attacks the carbon atom, displacing a proton H+ from that particular carbon atom. Nitration is thus called an electrophilic substitution reaction. Now a mixture of hydrogen gas and nitrobenzene vapors are heated at 600 °C in presence of a nickel catalyst. This gives aniline by reduction. Aniline obtained here is in the pure state.

PROPERTIES
Aniline is oily and, although colourless, it slowly oxidizes and resinifies in air, giving the sample a red-brown tint.

Like most volatile amines, it possesses a somewhat unpleasant odour of rotten fish, and also has a burning aromatic taste; it is a highly acrid poison. It ignites readily, burning with a smoky flame.

Chemically, aniline is a weak base. Aromatic amines such as aniline are generally much weaker bases than aliphatic amines. Aniline reacts with strong acids to form anilinium (or phenylammonium) ion (C₆H₅-NH3⁺), and reacts with acyl halides such as acetyl chloride to form amides. The amides formed from aniline are sometimes called anilides, for example CH₃-CO-NH-C₆H₅ is acetanilide.

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