See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Concept: Fischer esterification converts a carboxylic acid to an ester using an alcohol in the presence of an acid catalyst (H2SO4) with heat. The reaction is: R-COOH + CH3OH <-> R-COOCH3 + H2O. Step 1: Identify the starting material. The starting material is terephthalic acid (benzene-1,4-dicarboxylic acid), which has two -CO2H groups at the para positions of the benzene ring. Step 2: Identify the reagents. Two equivalents of methanol (2 CH3OH) are used with H2SO4 as acid catalyst and heat (Delta). Step 3: Determine the reaction outcome. With 2 equivalents of methanol and acid catalyst, both carboxylic acid groups undergo esterification. Each -CO2H group reacts with one CH3OH to form -CO2CH3. This converts both acid groups to methyl ester groups, giving dimethyl terephthalate: a benzene ring with -CO2CH3 at both para positions. Step 4: Evaluate the options: - Option (a): Shows one -CO2CH3 and one -CO2H (mono ester). This would be the product if only 1 equivalent of methanol were used. Incorrect. - Option (b): Shows -CO2CH3 at both para positions (1,4-dimethyl terephthalate). This is the correct product of esterifying both acid groups. Correct. - Option (c): Shows -CO2CH3 at meta positions (1,3-substitution pattern). The starting material is para-substituted, so this regiochemistry is impossible. Incorrect. - Option (d): Shows -C(=O)-CH3 (acetyl/ketone groups) at para positions. Methanol does not convert -COOH to a methyl ketone; that would require a different reagent. Incorrect. Step 5: With 2 equivalents of methanol provided and acid-catalyzed conditions, both -COOH groups are fully esterified to give dimethyl terephthalate, which matches option (b). Therefore, the correct answer is B.