Which organic compound will form yellow crystals during 'iodoform test'?
Correct answer: C. Ethanal
- A. Phenols
- B. Acetone
- C. Ethanal
- D. Methanol
Explanation
Positive iodoform test is given by a methyl ketone or a secondary alcohol with a methyl group in the alpha position. Option C is correct since Ethanal is the only aldehyde to give the triiodomethane (iodoform) reaction. All other options do not give yellow precipitate during the iodoform test; acetone cannot be distinguished by iodoform test as it contains methyl keto (CH3CO) group.
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About Reactivity of Aldehydes and Ketones
The polar carbonyl group makes aldehydes and ketones undergo nucleophilic addition, reduction and condensation reactions. Aldehydes are generally more reactive and oxidise readily to carboxylic acids, whereas ketones resist mild oxidation; reactions with hydrogen cyanide, sodium bisulfite and 2,4-DNP help identify their behaviour.
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