Consider the following reactions giving major product. Identify the correct reaction.

Solution

Chemistry ma’am · 3 steps

Test each reaction against its named rule. Only the Hofmann bromamide equation survives the check.

1. The approach. Each option is a standard named reaction with one detail that may be wrong. Ask what that reaction actually gives, then compare it with the product drawn.

   Option	Reaction	What really happens	Verdict
   (a)	Nitration of benzanilide, PhCONHPh	N lone pair activates the N-phenyl ring. C=O deactivates the benzoyl ring. So NO₂ goes para on the N-phenyl ring.	wrong
   (b)	Carbylamine reaction, then Sn/HCl	PhCH₂NC forms, but reducing an isocyanide gives the secondary amine PhCH₂NHCH₃, not PhCH₂NH₂.	wrong
   (c)	Gabriel synthesis with an aryl halide	The phthalimide anion needs S_N2 attack. Aryl halides do not undergo it, so aniline cannot be made this way.	wrong
   (d)	Hofmann bromamide degradation	RCONH₂ + Br₂ + 4KOH → RNH₂ + K₂CO₃ + 2KBr + 2H₂O. The amine has one carbon fewer than the amide.	correct

2. Check (d). Propanamide, CH₃CH₂CONH₂, has 3 carbons. It loses the carbonyl carbon as K₂CO₃ and gives ethylamine, CH₃CH₂NH₂, with 2 carbons. The equation also balances: 4 K, 2 Br, 5 O and 11 H on each side.
3. So. Only (d) is a correct reaction with the correct major product.

The idea to keep. Hofmann bromamide removes one carbon from the amide. Isocyanides reduce to N-methyl secondary amines. Gabriel synthesis works only for primary alkyl amines, never for aryl amines.

Answer from the NTA final answer key. Solution by PrepWiser.