See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Step 1 - Concept: This reaction sequence involves the reaction of a carboxylic acid with LiH (lithium hydride) in dimethoxyethane (DME), followed by methylation with CH3Br, and then acidic hydrolysis. Step 2 - Formation of L: LiH is a strong base/hydride source. When cyclohexanecarboxylic acid reacts with LiH in dimethoxyethane, the acidic proton of the carboxylic acid is removed to form the lithium carboxylate salt (lithium cyclohexanecarboxylate). This is compound L: cyclohexyl-COO-Li+. Step 3 - Formation of M: The lithium carboxylate (L) reacts with CH3Br (methyl bromide) via O-alkylation (since the carboxylate oxygen is the nucleophile). The carboxylate anion reacts with CH3Br to give the methyl ester: cyclohexyl-C(=O)-O-CH3. This is compound M. Step 4 - Formation of N: M (the methyl ester, cyclohexyl-C(=O)-OCH3) is treated with H3O+ (aqueous acid). However, simple acid hydrolysis of a methyl ester would regenerate the carboxylic acid and methanol. The products are cyclohexanecarboxylic acid (N) and CH3OH. This matches option (c): cyclohexyl-C(=O)-O-H (cyclohexanecarboxylic acid). Step 5 - Why other options fail: - Option (a) cyclohexyl-CH3: This would require reduction, not the chemistry described. - Option (b) cyclohexyl-C(=O)-CH3 (methyl ketone): This would require a different reaction pathway (e.g., reaction with organolithium on an ester), not simple ester hydrolysis. - Option (d) cyclohexyl-CH(OH)-CH3: This would require nucleophilic addition of a methyl group to a carbonyl, not acid hydrolysis. The sequence is: RCOOH + LiH → RCOOLi (L) + H2; RCOOLi + CH3Br → RCOOCH3 (M) + LiBr; RCOOCH3 + H3O+ → RCOOH (N) + CH3OH. N is cyclohexanecarboxylic acid, which is option (c). Therefore, the correct answer is C.