See image — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the starting material: The starting material is 4-nitrobenzyl cyanide, i.e., a benzene ring bearing a -CH2CN group and a para -NO2 group. Wait - looking more carefully at the structure, the CN is directly attached to the ring (not via CH2), making it 4-nitrobenzonitrile (ArCN where Ar = 4-NO2-C6H4). Step 2 - Step (1): Treatment with HO- (1 mole). Hydroxide acts as a nucleophile on the nitrile group. Under basic hydrolysis conditions, ArCN + HO- first gives the amide (ArCONH2) as an intermediate, or in the context of the Hofmann-like sequence, partial hydrolysis yields the primary amide ArCONH2. Step 3 - Step (2): Treatment with HO- and Br2. This is the classic Hofmann degradation (Hofmann rearrangement) conditions. A primary amide (ArCONH2) reacts with Br2 in the presence of base (HO-) to give a primary amine (ArNH2) with loss of CO2. The mechanism involves N-bromination of the amide, followed by rearrangement and hydrolysis: ArCONH2 + Br2 + 4HO- → ArNH2 + CO3^2- + 2Br- + 2H2O. Step 4 - Identify the product: Starting from 4-nitrobenzonitrile, partial hydrolysis gives 4-nitrobenzamide, and Hofmann degradation gives 4-nitroaniline (a benzene ring with NH2 at C1 and NO2 at C4). Step 5 - Match to options: Option (c) shows a benzene ring with NH2 at position 1 and NO2 at position 4, which is 4-nitroaniline. This matches. Why other options fail: - (a) shows 4-aminobenzoate, which would require reduction of NO2 and hydrolysis of CN to COO-, not consistent with these conditions. - (b) shows 1,4-dinitrobenzene, which has no nitrogen source for a second NO2 and is not a product of these reactions. - (d) shows 4-bromonitrobenzene, which would require substitution on the ring, not consistent with these conditions. Therefore, the correct answer is C.