Cyanohydrin formation and nitrile hydrolysis extend the carbon chain to a branched carboxylic acid

Steps:

• Propanone ((CH3)2C=O) adds HCN across the carbonyl to form the cyanohydrin (CH3)2C(OH)CN.
• The -CN group undergoes acidic hydrolysis (H3O+, heat) to -COOH.
• This replaces the carbonyl oxygen with -CH(CN) effectively, but hydrolysis yields the extended chain (CH3)2CHCOOH.
• The reaction increases the carbon count by one, forming 2-methylpropanoic acid.

Why D is correct:

• Nitrile hydrolysis under acidic conditions converts -CN to -COOH, extending propanone's chain to the branched C4 acid (CH3)2CHCOOH per standard organic transformation.

Why the others are wrong:

• A: Product from propanal (aldehyde) cyanohydrin hydrolysis, not propanone.
• B: Propanoic acid from propanone oxidation, no chain extension.
• C: Isopropanol from propanone reduction, no HCN involvement.

Final answer: D