In the iodoform test, a yellow precipitate is given by
- A. any primary alcohol
- B. methanol
- C. ethanol and other alcohols containing the CH3CH(OH) group
- D. all tertiary alcohols
Explanation
The test needs a methyl group attached to the carbon bearing the hydroxyl, so ethanol and propan-2-ol respond while methanol and propan-1-ol do not. Iodine in alkali oxidises and then cleaves the molecule, leaving the yellow crystalline triiodomethane. Methyl ketones give the same positive result for the same structural reason.
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