Identify the major product E in the following reaction sequence: Aniline Ac ₂ O , Pyridine A Br ₂, CH ₃ COOH B (major) H ₃ O ^+ C [273 - 278 K ] NaNO ₂, HCl D H ₃ PO ₂, H ₂ O E

Step-by-step solution

Reaction of aniline with acetic anhydride in the presence of pyridine protects the - NH ₂ group, forming acetanilide (A). Bromination of acetanilide with Br ₂ in acetic acid yields 4-bromoacetanilide (B) as the major product due to steric hindrance at the ortho positions. Acidic hydrolysis of (B) removes the acetyl group, yielding 4-bromoaniline (C). Diazotization of (C) with NaNO ₂ and HCl at 273-278 K forms 4-bromobenzenediazonium chloride (D). Treatment of the diazonium salt (D) with hypophosphorous acid ( H ₃ P