Question

Write the preparation method of nitro benzene. Explain any three reduction properties of nitrobenzene with equation.

Answer 1

The nitrobenzene is the aromatic compound where a nitro group is present in a benzene ring. The nitrobenzene can be obtained from benzene by the process of nitration reaction.

Complete step by step answer:
The nitro benzene is prepared from benzene by the process of nitration. Nitration is the process, where a nitro group substitutes the hydrogen of the aromatic ring compound by reacting with nitric acid and sulphuric acid. First in the reaction, nitric acid reacts with sulphuric acid to form nitronium ion.
The reaction for the preparation of nitrobenzene is shown below.
${C_6}{H_6}\xrightarrow[{50^\circ C}]{{conc.HN{O_3} + conc.{H_2}S{O_4}}}{C_6}{H_5} - N{O_2} + {H_2}O$
In this reaction, benzene reacts with concentrated nitric acid and concentrated sulphuric acid to form nitrobenzene as the main product and water as by product.
Nitrobenzene shows reduction in reaction to form new compounds.
The nitrobenzene is reduced to aniline by reacting with tin in a strong acidic medium of hydrochloric acid.
The reaction for the reduction of nitrobenzene to aniline is shown below.
${C_6}{H_5} - N{O_2} + 6[H]\xrightarrow{{Sn + HCl}}{C_6}{H_5} - N{H_2} + 2{H_2}O$
The nitrobenzene is reduced to nitrobenzene in presence of zinc dust and ammonium chloride. The nitrobenzene is then reduced to phenylhydroxylamine.
The reaction for the reduction of nitrobenzene to phenylhydroxylamine is shown below.
${C_6}{H_5} - N{O_2}\xrightarrow{{Zn\;dust + N{H_4}Cl}}{C_6}{H_5} - N = O\xrightarrow{{2[H]}}{C_6}{H_5} - NH - OH$
In this reaction, nitro benzene is first converted to nitrobenzene by reacting with zinc dust and ammonium chloride. The nitrobenzene is then further reduced to phenyl hydroxylamine.
The nitrobenzene is reduced to give a mixture of compound nitrobenzene and phenyl hydroxylamine.
The reaction for the reduction of nitrobenzene to nitrosobenzene and phenyl hydroxyl amine is shown below.
${C_6}{H_5} - N{O_2}\xrightarrow{{Zn + NaOH}}{C_6}{H_5} - N = O + {C_6}{H_5} - NH - OH$
In this reaction, nitro benzene is reacted with zinc and sodium hydroxide to form a mixture of nitrosobenzene and phenyl hydroxylamine.

Note:
Make sure that during the preparation of nitrobenzene from benzene, the temperature should be below $100^\circ C$. If the temperature exceeds beyond $100^\circ C$ then meta dinitrobenzene is formed.