Select the compound that will give a Positive iodoform test:
Correct answer: B. 2-Pentanone
- A. Benzaldehyde
- B. 2-Pentanone
- C. 3-Hexanone
- D. 3-Pentanone
Explanation
The iodoform test is a chemical reaction used to identify methyl ketones, which contain a CH3 group directly bonded to the carbonyl carbon. 2-Pentanone is the only compound among the options that has this structure, allowing it to undergo the necessary halogenation and subsequent hydrolysis to form iodoform (CHI3), which is a yellow precipitate. Benzaldehyde, 3-Hexanone, and 3-Pentanone do not have the requisite alpha-methyl group, and therefore, do not give a positive iodoform test.
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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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