COMEDK 2025 Morning Solved Paper

Concept:The reaction that does not give the correct combination of reactants and major products is identified by checking the reducing ability of DIBAL‑H.Explanation:Option C is incorrect.DIBAL‑H at low temperature selectively reduces a nitrile ($-\mathrm{CN}$) to an aldehyde ($-\mathrm{CHO}$) without affecting a carbon‑carbon double bond ($\mathrm{C}=\mathrm{C}$).The starting reactant is $\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CN}$.After reduction with DIBAL‑H followed by hydrolysis, the major product should be $\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CHO}$ (an unsaturated aldehyde).However, the given product is $\mathrm{CH}_3-\left(\mathrm{CH}_2\right)_4-\mathrm{CHO}$, which is a fully saturated aldehyde.Thus, the product shown does not match the expected outcome of the reaction.Answer:Option C