Question

Which of the following reaction/s will not give p-aminoazobenzene ? 

• A. A only
• B. c only
• C. B only
• D. A and B

Hint:

$Sn/HCl$ or $Fe/HCl$ are the preferred reagents for reducing $-NO_2$ to $-NH_2$ on aromatic rings while keeping other sensitive groups intact.

Answer 1

The Correct Option is B

Step 1: (A) $Sn/HCl$ reduces the nitro group to an amino group without breaking the azo bond ($N=N$). This produces p-aminoazobenzene.
Step 2: (C) Reacting p-nitroaniline with $HNO_2$ creates a diazonium salt on the nitro-carrying ring, but the coupling with aniline occurs at the para position, potentially leading to the product after further steps.
Step 3: (B) $NaBH_4$ is a selective hydride reducer that typically does not reduce aromatic nitro groups or azo groups to amines efficiently.