JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Chapter_pending

Acid-catalysed hydrolysis cleaves an ester to its parent acid and alcohol, so ethyl acetate with ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4/{\mathrm{H}}_2\mathrm{O}$ gives ethanol. DIBAL-H delivers a single hydride to an ester carbonyl and the tetrahedral intermediate survives at low temperature, collapsing only on aqueous work-up, so methyl acetate stops at ethanal instead of going on to the alcohol. Stephen's reduction with $\mathrm{SnC}{\mathrm{l}}_2$ and HCl converts a nitrile to an aldimine that hydrolyses to the aldehyde, so acetonitrile gives ethanal. One equivalent of a Grignard reagent adds to an $N,N$-disubstituted amide and the adduct breaks down on acidic work-up to a ketone, so $N,N$-dimethylacetamide with $\mathrm{C}{\mathrm{H}}_3\mathrm{MgBr}$ gives propanone. Ethyl acetate to ethanol pairs with ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4/{\mathrm{H}}_2\mathrm{O}$, methyl acetate to ethanal with DIBAL-H$/{\mathrm{H}}_2\mathrm{O}$, acetonitrile to ethanal with $\mathrm{SnC}{\mathrm{l}}_2$, HCl$/{\mathrm{H}}_2\mathrm{O}$, and $N,N$-dimethylacetamide to propanone with $\mathrm{C}{\mathrm{H}}_{3}MgBr/{\mathrm{H}}_3{\mathrm{O}}^{+}$.