Role of CH3CO2H in alkene formation via elimination

Steps:

• Identify the reaction as E2 elimination from a vicinal dihalide or alkyl halide to form hex-2-ene.
• Note CH3CO2H provides CH3CO2⁻ ions, which abstract a proton from the β-carbon.
• Confirm bond breaking: C-H heterolytic, C-I heterolytic, forming C=C double bond.
• Classify CH3CO2⁻ as proton acceptor, making it a Brønsted-Lowry base.

Why A is correct:

• CH3CO2H dissociates to CH3CO2⁻ + H⁺; CH3CO2⁻ accepts H⁺ from substrate, fitting Brønsted-Lowry base definition (proton acceptor).

Why the others are wrong:

• B: No change in oxidation state of carbon; it's elimination, not oxidation.
• C: E2 involves heterolytic fission of C-I bond, not homolytic (which forms radicals).
• D: Hydrolysis adds water across a bond; this is dehydration-like elimination without net water addition.

Final answer: A