See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the starting material: The starting material is an ester formed between 4-nitrobenzoic acid and the primary alcohol of (1-methyl-3-oxocyclohex-2-en-1-yl)methanol. The alcohol carbon bearing the -CH2O- group is also attached to a methyl group and is part of a cyclohexenone ring (unsaturated ketone). Step 2 - Reaction with H2 / Wilkinson's catalyst [(Ph3P)3RhCl]: Wilkinson's catalyst is a homogeneous hydrogenation catalyst that selectively reduces isolated (non-conjugated) C=C double bonds and also reduces conjugated alkene-carbonyl systems (enones) under certain conditions. However, Wilkinson's catalyst is known to selectively hydrogenate the C=C double bond of the enone (the alkene portion) without reducing the ester, the nitro group, or the carbonyl (ketone). The C=C double bond in the cyclohexenone ring is hydrogenated, converting the cyclohex-2-enone ring into a cyclohexanone ring. The nitro group and ester linkage remain intact. Product (A) is therefore the fully saturated ester: 4-nitrobenzoic acid esterified with (1-methyl-3-oxocyclohexan-1-yl)methanol. Step 3 - Reaction of (A) with 0.1 M NaOH / H2O (Methanol): This is saponification (base-catalyzed hydrolysis) of the ester. The ester bond is cleaved to give: the carboxylate salt of 4-nitrobenzoic acid [4-NO2-C6H4-COO(-) Na(+)] as product (B), and the alcohol (1-methyl-3-oxocyclohexan-1-yl)methanol as product (C). Product (C) contains no nitrogen, consistent with the problem statement. Step 4 - Identify Product (B): The saponification of an ester with NaOH gives the carboxylate anion. Product (B) is the 4-nitrobenzoate anion: a benzene ring bearing CO2(-) at one position and NO2 at the para position. This matches option (b). Step 5 - Identify Product (C): The alcohol released is (1-methyl-3-oxocyclohexan-1-yl)methanol - a fully saturated cyclohexanone with a -CH2OH group and a methyl group on the same carbon (C1). The structure shows CH2OH (primary alcohol, -CH2-OH extending from the quaternary carbon) attached to a methyl-bearing carbon in a cyclohexanone ring (fully saturated, no double bond). This matches option (b) for part B: the structure showing OH on a CH2 group, methyl on the same carbon, fully saturated cyclohexanone ring. Step 6 - Why other options for (B) fail: (a) 4-nitrophenol would require reduction of the ester to phenol, which doesn't happen under mild NaOH hydrolysis. (c) Methyl 4-nitrobenzoate would form only if methanol acted as nucleophile in transesterification under basic conditions, which is not the primary product of saponification. (d) is the unreacted starting ester. Step 7 - Why other options for (C) fail: (a) still has the double bond in the ring, but Wilkinson's catalyst reduced it in step 1. (c) and (d) have the OH on a secondary or tertiary carbon attached directly to the ring rather than on a CH2 group, which doesn't match the alcohol liberated from this ester. Therefore, the correct answer is {"A": ["B"], "B": ["B"]}.