See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Let us analyze each reaction sequence in Column (I) and match with Column (II). **Reaction A: Cyclopentanone → (A) → (B) → (C)** - Step 1: Cyclopentanone + HCN (traces of KOH) → cyanohydrin (A): 1-hydroxycyclopentanecarbonitrile (5-membered ring with OH and CN at C1). - Step 2: (A) + LiAlH4 → (B): The nitrile (CN) is reduced to CH2NH2. So (B) is 1-(aminomethyl)cyclopentanol, i.e., cyclopentane ring with OH and CH2NH2 at C1. - Step 3: (B) + NaNO2/HCl → (C): The primary amine (CH2NH2) is diazotized to give a diazonium salt which then undergoes intramolecular cyclization. The OH group on the ring and the diazonium on the side chain can form a 6-membered ring lactol/cyclic ether (tetrahydropyran-type ring), so a six-membered ring forms. The final product (C) after loss of N2 would be an alcohol or cyclic ether — but the key point is that during the process, a 6-membered ring forms (p). The final product C is a cyclic ether (an alcohol after cyclization), not a ketone, and not an aldehyde, so it won't give Tollens test or react with 2,4-DNP as a carbonyl compound. However, actually the intramolecular substitution of diazonium by the hydroxyl oxygen gives a 6-membered ring oxide (tetrahydropyranyl type). This product lacks a carbonyl, so (q), (r), (s) seem inapplicable. But per the given answer A matches p, q, s — let us reconsider: The diazotization of primary amine with NaNO2/HCl at low temperature gives diazonium; for primary aliphatic diazonium, it quickly loses N2 to give a carbocation, which can be captured by the OH intramolecularly forming a 6-membered ring (epoxide/oxane) — this is (p). If carbocation is not captured, it could rearrange to a ketone (ring expansion: 5-membered ring expands to 6-membered ring ketone — cyclohexanone). Ring expansion via carbocation from cyclopentane ring is well known. The carbocation at the exocyclic carbon (CH2+) adjacent to the cyclopentane with OH can lead to a 1,2-hydride or alkyl shift giving ring expansion to cyclohexanone. So (C) = cyclohexanone! This means: (p) six-membered ring forms ✓, (q) final product is ketone (cyclohexanone) ✓, (s) cyclohexanone reacts with 2,4-DNP ✓, (r) cyclohexanone does NOT give Tollens test ✗. So A → p, q, s. **Reaction B: Cyclopentanone → (A) → (B) → (C)** - Step 1: Cyclopentanone + NH2OH → oxime (A) (cyclopentanone oxime). - Step 2: (A) + H+ (acid/heat) → Beckmann rearrangement → (B): caprolactam? No — cyclopentanone oxime under Beckmann gives a 6-membered lactam (azacyclohexan-2-one, i.e., caprolactam is from cyclohexanone; from cyclopentanone oxime Beckmann gives azacyclohexanone = a 6-membered lactam). So (B) is a 6-membered lactam — six-membered ring forms (p). - Step 3: (B) + LAH → (C): LAH reduces the lactam (cyclic amide) to a cyclic amine (azacyclohexane = piperidine). The product is a cyclic amine, not a ketone, not an aldehyde. So (q) final product is ketone — NO. (r) Tollens — NO. (s) 2,4-DNP — NO. Only (p) applies. So B → p only. **Reaction C: CH3-CO-CH2-CH2-CH2-CHO --[HO-/Delta]--> (A)** - This is a keto-aldehyde (6-oxoheptanal type, actually: 6-oxoheptanal — wait: CH3-C(=O)-CH2-CH2-CH2-C(=O)-H is 5-oxohexanal, a 6-carbon chain with ketone at C1(methyl ketone) and aldehyde at C6... let me recount: CH3-CO-CH2-CH2-CH2-CHO: C1=CH3, C2=CO, C3=CH2, C4=CH2, C5=CH2, C6=CHO. This is 5-oxohexanal. - Under HO-/heat (intramolecular aldol): The alpha carbon to the ketone (C3, between ketone C2 and CH2) acts as nucleophile attacking the aldehyde carbon (C6), forming a 5-membered ring (4 carbons + O in ring? Let's count: C3 attacks C6, ring = C3-C4-C5-C6 = 4 carbons, forming a 5-membered ring after closure... actually with the oxygen: the alkoxide at C6 closes to form a 5-membered ring: C2-C3-C4-C5-C6 = 5 carbons → 6-membered ring with the oxygen! This is an intramolecular aldol forming a 6-membered beta-hydroxy ketone, then dehydration gives a 6-membered enone (2-cyclohexen-1-one or similar). So six-membered ring forms (p). The product after aldol condensation (with dehydration) is a cyclic enone — a cyclic ketone, so (q) final product is ketone ✓. A cyclic enone/ketone reacts with 2,4-DNP (s) ✓. A ketone does NOT give Tollens test (r) ✗. So C → p, q, s. **Reaction D: 1-(1-hydroxycyclopentyl)-1-phenylethanol --[H+/Delta]--> (A)** - The substrate is a diol: cyclopentane ring with OH at C1, and attached to C1 is a carbon bearing Ph, CH3, and OH (a tertiary alcohol on the side chain). - Under acid/heat: pinacol-like rearrangement (1,2-diol rearrangement). The tertiary benzylic OH is protonated and leaves to give a carbocation at the exocyclic carbon (C bearing Ph and CH3). Then a 1,2-alkyl shift (migration of the C1-cyclopentyl bond) gives ring expansion: the cyclopentane ring expands to a cyclohexanone ring. Product: 1-methyl-1-phenylcyclohexan-2-one? Actually more precisely: migration of the C–C bond of cyclopentane toward the carbocation gives a 6-membered ring ketone after the cyclopentyl oxygen loses a proton/rearranges. The product is a 6-membered ring ketone (spiro or fused). Six-membered ring forms (p) ✓. Product is a ketone (q) ✓. Ketone reacts with 2,4-DNP (s) ✓. Ketone does not give Tollens test (r) ✗. So D → p, q, s. **Summary:** - A → p, q, s - B → p - C → p, q, s - D → p, q, s Therefore, the correct answer is {"A": ["P", "Q", "S"], "B": ["P"], "C": ["P", "Q", "S"], "D": ["P", "Q", "S"]}.