Why is the reduction of nitrobenzene to aniline using iron scrap and hydrochloric acid (Fe + HCl) industrially preferred over tin and hydrochloric acid (Sn + HCl)?

Answer and explanation

Correct answer: A. FeCl2 hydrolyzes to regenerate HCl so only a catalytic amount of acid is required

$Fe + 2HCl \rightarrow FeCl_2 + 2[H]$.
  1. Step 1: Both and reduce nitro compounds to primary amines: .
  2. Step 2: In the industrial reduction using iron scrap and :
  3. Step 3: The ferrous chloride () formed undergoes in situ aqueous hydrolysis: .
  4. Step 4: Because hydrochloric acid is continuously regenerated by this hydrolysis cycle, only a small catalytic initiating amount of is required, making the iron scrap process extremely economical and industrially favored.
Answer
The FeCl2 produced during the reaction is hydrolyzed by water to regenerate HCl, requiring only a small catalytic amount of hydrochloric acid to initiate the process
Why not the others: 'Tin produces radioactive lead isotopes...' is false as tin-120 is stable and non-radioactive; 'Iron scrap evaporates, leaving pure gaseous aniline...' is physically absurd; 'Tin forms explosive trinitrotoluene...' is chemically fabricated.

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