MHTCET 5 May 2025 Shift 2 Paper

Concept:This is a Friedel-Crafts acylation reaction, where an acyl group is introduced on an aromatic ring in the presence of anhydrous $\mathrm{AlCl}_3$.Explanation:Acetyl chloride, $\mathrm{CH_3COCl}$, reacts with an aromatic compound to form an acetophenone derivative. The product is 2-chloroacetophenone and 4-chloroacetophenone, which means the acetyl group enters at positions ortho and para to a chlorine atom on the ring. Therefore, the starting aromatic compound must already contain a chlorine substituent. Chlorobenzene, $\mathrm{C_6H_5Cl}$, directs the incoming acetyl group to the ortho and para positions, giving exactly these two products. Benzene would give only acetophenone, toluene would give methylacetophenones, and phenol would give hydroxyacetophenones. Answer:A is Chlorobenzene.Correct option: B. Chlorobenzene.