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Most Important Selected Qs for JEE AdvancedChemistryAldehydes and Ketones

Paragraph: Consider the following mechanism of an aldol condensation reaction: Answer the following questions based on the above mechanism and your knowledge about aldol condensation. Question: If all the alpha hydrogen in X is replaced by deuterium "D" atom. Which of the following would be observed? (Assuming high concentration of base)

Options

  1. AEnolate I is more stable than II, since it is formed by deprotonation of more acidic hydrogen.
  2. BEnolate I is more stable than II, since it is less substituted.
  3. CEnolate II is more stable than I, since it is formed by deprotonation of more stable than acidic hydrogen.
  4. DEnolate II is more stable than I, since it is more substituted.

Correct answer

D. Enolate II is more stable than I, since it is more substituted.

Step-by-step solution

C - H bond is broken in non rate determining step, therefore, substitution of - H by deuterium doesn't affect the rate of reaction.

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