Question:
The compound that does not undergo haloform reaction is
The compound that does not undergo haloform reaction is
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Always look for the "Methyl group sitting next to the Carbonyl" to identify haloform-positive compounds.
Updated On: Apr 29, 2026
- acetaldehyde
- ethanol
- acetone
- acetophenone
- propiophenone
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The Correct Option is
Solution and Explanation
Concept:
The haloform reaction requires the presence of a methyl keto group (\(CH_3-CO-\)) or a grouping that can be oxidized to it, like a methyl carbinol (\(CH_3-CH(OH)-\)).
Step 1: Check the functional groups.
• Acetaldehyde (A): \(CH_3-CHO\) (Has the methyl keto structure).
• Ethanol (B): \(CH_3-CH_2OH\) (Can be oxidized to acetaldehyde).
• Acetone (C): \(CH_3-CO-CH_3\) (Has two methyl keto groups).
• Acetophenone (D): \(C_6H_5-CO-CH_3\) (Has the methyl keto group).
Step 2: Analyze Propiophenone (E).
The structure of propiophenone is: \[ C_6H_5-CO-CH_2-CH_3 \] This molecule contains an ethyl keto group, not a methyl keto group. The carbon attached to the carbonyl is part of a \(CH_2\) group.
Step 3: Conclusion.
Because it lacks the specific \(CH_3-CO-\) arrangement, it cannot form a trihalomethyl intermediate (\(CX_3-CO-\)) which is necessary to produce the haloform (\(CHX_3\)).
Step 1: Check the functional groups.
• Acetaldehyde (A): \(CH_3-CHO\) (Has the methyl keto structure).
• Ethanol (B): \(CH_3-CH_2OH\) (Can be oxidized to acetaldehyde).
• Acetone (C): \(CH_3-CO-CH_3\) (Has two methyl keto groups).
• Acetophenone (D): \(C_6H_5-CO-CH_3\) (Has the methyl keto group).
Step 2: Analyze Propiophenone (E).
The structure of propiophenone is: \[ C_6H_5-CO-CH_2-CH_3 \] This molecule contains an ethyl keto group, not a methyl keto group. The carbon attached to the carbonyl is part of a \(CH_2\) group.
Step 3: Conclusion.
Because it lacks the specific \(CH_3-CO-\) arrangement, it cannot form a trihalomethyl intermediate (\(CX_3-CO-\)) which is necessary to produce the haloform (\(CHX_3\)).
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