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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3co244

The ketone shown is considered. Which statements are correct?

  1. AIt has two enolisable positions (the CH3 and the CH)
  2. BExcess I2/NaOH followed by acidification gives 2-methylpropanoic acid
  3. CWith LDA at low temperature the kinetic enolate forms at the CH3 side, while equilibrating conditions favour the more substituted (CH) enolate
  4. DIt has six alpha-hydrogens in total

Answer: A, B, C

The drawn compound is 3-methylbutan-2-one. Alpha carbons: CH3 (3 H) and CH (1 H), so 4 alpha-hydrogens, not 6 (RDKit count). It is a methyl ketone, so the haloform reaction gives (CH3)2CHCOO(-) and then the acid. Kinetic deprotonation is at the less hindered CH3; the thermodynamic enolate is the more substituted one. So 1, 2, 3 are correct.
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