MHTCET 19 Apr 2026 Shift 2 Paper

Concept:Hofmann degradation is the reaction where an amide loses its carbonyl group to form a primary amine.Explanation:In Hofmann degradation, a primary amide is treated with bromine and a strong alkali.The carbonyl group $-\mathrm{CO}-$ is removed from the amide, and the alkyl group attaches to the nitrogen atom.This produces a primary amine with one carbon atom less than the starting amide.The general reaction is:$$\mathrm{RCONH}_{2}+\mathrm{Br}_{2}+4\mathrm{KOH} \rightarrow \mathrm{RNH}_{2}+2\mathrm{KBr}+\mathrm{K}_{2}\mathrm{CO}_{3}+2\mathrm{H}_{2}\mathrm{O}$$Other options do not involve the removal of a $-\mathrm{CO}-$ group.Gabriel phthalimide synthesis and ammonolysis of halides form amines without removing a carbonyl group.Mendius reduction reduces nitriles to amines without carbonyl removal.Thus, the reaction that occurs by removal of $-\mathrm{CO}-$ group from amide is Hofmann degradation.Answer:Option D – Hofmann degradation