Which of the following compounds is most likely to undergo a haloform reaction?

• A. ${\mathrm{CH}}_3\mathrm{COCH}{3}_{}$ (acetone)
• B. ${\mathrm{CH}}_3\mathrm{COOH}$ (acetic acid)
• C. ${\mathrm{CH}}_3\mathrm{OCH}{3}_{}$ (dimethyl ether)
• D. ${\mathrm{CH}}_3\mathrm{CH}{2}_{}\mathrm{OH}$ (ethanol)

Answer: (A)

Verified step by step guidance

1. Understand the haloform reaction: it occurs when a methyl ketone (a compound with the structure R-CO-CH3) reacts with halogen and base, producing a haloform (like CHCl3, CHBr3) and a carboxylate ion.
2. Identify the functional groups in each compound: acetone (CH3COCH3) is a methyl ketone, acetic acid (CH3COOH) is a carboxylic acid, dimethyl ether (CH3OCH3) is an ether, and ethanol (CH3CH2OH) is an alcohol.
3. Recall that the haloform reaction specifically requires a methyl ketone group (R-CO-CH3) to proceed efficiently, because the alpha hydrogens adjacent to the carbonyl are necessary for halogenation and subsequent cleavage.
4. Evaluate each compound: acetone has the methyl ketone structure, acetic acid lacks the ketone carbonyl, dimethyl ether has no carbonyl group, and ethanol is an alcohol without a carbonyl group.
5. Conclude that acetone is the compound most likely to undergo the haloform reaction due to its methyl ketone functional group.