See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Concept: This is a multi-step organic synthesis problem involving nucleophilic substitution, hydrolysis, and esterification. Step 2 - First reaction (CH3CH2CH2Br + NaCN → X): 1-bromopropane undergoes SN2 reaction with sodium cyanide (NaCN) as a nucleophile. The cyanide ion displaces the bromide, giving CH3CH2CH2CN (butanenitrile). So X = CH3CH2CH2CN. Step 3 - Second reaction (X + H3O+/heat → Y): The nitrile (CH3CH2CH2CN) undergoes acid-catalyzed hydrolysis under aqueous acidic conditions with heat. Nitriles hydrolyze to carboxylic acids under these conditions: CH3CH2CH2CN + H3O+/heat → CH3CH2CH2COOH (butanoic acid). So Y = CH3CH2CH2COOH. Step 4 - Third reaction (Y + CH3CH2OH/H+ → Z): Butanoic acid reacts with ethanol (CH3CH2OH) in the presence of an acid catalyst (H+) in a Fischer esterification. The carboxylic acid reacts with ethanol to form an ester: CH3CH2CH2COOH + CH3CH2OH → CH3CH2CH2COOCH2CH3 + H2O. So Z = CH3CH2CH2COOCH2CH3 (ethyl butanoate). Step 5 - Matching to options: Z = CH3CH2CH2C(=O)OCH2CH3, which corresponds to option (d). Step 6 - Why other options fail: - Option (a) CH3CH=CHC(=O)OH is crotonic acid, which would require different starting conditions and an elimination step not present here. - Option (b) CH3CH2CH2CH=NOCH2CH3 is an oxime ether, which would require reaction with a hydroxylamine derivative, not ethanol/H+. - Option (c) CH3CH2CH2CH(OCH2CH3)2 is an acetal, which forms from an aldehyde with ethanol/H+, not from a carboxylic acid. - Option (d) correctly represents the ester product of butanoic acid with ethanol. Therefore, the correct answer is D.