The anhydride shown is first warmed with one equivalent of methanol (no catalyst), and the product is then refluxed with excess ethanol and conc. $H X_{2} SO X_{4}$ . Which structure is the final organic product?

AStructure A
BStructure B
CStructure C
DStructure D

Answer: A

The drawn compound is phthalic anhydride. One equivalent of methanol opens the ring to the mono-methyl ester carboxylic acid. Fischer esterification of the free COOH with ethanol then gives the mixed diester, methyl ethyl phthalate. Under these conditions the methyl ester is not exchanged (transesterification is slow relative to esterification of the acid).

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The anhydride shown is first warmed with one equivalent of methanol (no catalyst), and the product is then refluxed with excess ethanol and conc. HX2​SOX4​. Which structure is the final organic product?

Answer: A

More questions on Acidity order and derivative reactivity among drawn carboxylic acids

The anhydride shown is first warmed with one equivalent of methanol (no catalyst), and the product is then refluxed with excess ethanol and conc. $H X_{2} SO X_{4}$ . Which structure is the final organic product?