Among the following, which is the correct set of reducing agents for conversion of nitrobenzene into aniline?
(A) \( H_2/Pd \)
(B) \( Sn+HCl \)
(C) \( Fe +HCl \)
(D) \( NaBH_4 \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B) and (C) only
A nitro group is reduced to an amino group by catalytic hydrogenation or by a metal in acid; a mild hydride reagent does not do it.
(A) \(H_2/Pd\) — Correct. Hydrogen on a palladium catalyst reduces the nitro group:
\( \displaystyle \ce{C6H5NO2 + 3H2} \xrightarrow{\ce{Pd}} \ce{C6H5NH2 + 2H2O} \)
(B) \(Sn+HCl\) — Correct. Tin and hydrochloric acid supply the hydrogen:
\( \displaystyle \ce{C6H5NO2 + 6[H]} \xrightarrow{\ce{Sn + HCl}} \ce{C6H5NH2 + 2H2O} \)
(C) \(Fe +HCl\) — Correct. Iron and hydrochloric acid reduce the nitro group in the same way; this is the method preferred in practice:
\( \displaystyle \ce{C6H5NO2 + 6[H]} \xrightarrow{\ce{Fe + HCl}} \ce{C6H5NH2 + 2H2O} \)
(D) \(NaBH_4\) — Incorrect. Sodium borohydride is a mild hydride reagent that reduces aldehydes and ketones; it does not reduce an aromatic nitro group to an amine.
NCERT (2026-27 edition):
Reduction of Nitro Compounds
