Chemistry - Carboxylic acid and their Derivatives Question with Solution | TestHub

The last product is 1-hydroxycyclopentanecarbonitrile, so D is cyclopentanone. Dimethyl adipate A undergoes intramolecular Claisen (Dieckmann) condensation to a five-membered beta-keto ester B, then hydrolysis gives beta-keto acid C and heating decarboxylates to D. HCN adds to D. The ethyl succinate alternatives give the wrong ring size/ester alcohol. Thus A.