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JEE MainChemistryAldehydes and Ketones

Consider the following reaction sequence: 2,6-Heptanedione (i) dil. NaOH, A (ii) NaCN (iii) H ₃ O ^+, Product B Which of the following statements correctly describes product B?

Options

  1. AIt is a meso compound and gives effervescence with saturated NaHCO ₃ solution.
  2. BIt is optically active and gives a yellow precipitate with I ₂/ NaOH .
  3. CIt is a racemic mixture and gives a yellow precipitate with I ₂/ NaOH .
  4. DIt is a racemic mixture, gives effervescence with saturated NaHCO ₃ solution, and does not respond to the iodo

Correct answer

D. It is a racemic mixture, gives effervescence with saturated NaHCO ₃ solution, and does not respond to the iodo

Step-by-step solution

2,6-Heptanedione undergoes intramolecular aldol condensation in the presence of dilute NaOH and heat. The enolate formed at one of the terminal methyl groups attacks the other carbonyl carbon, forming a 6-membered ring. Dehydration yields 3-methylcyclohex-2-en-1-one (Compound A). Compound A is an , -unsaturated ketone. Reaction with NaCN results in a 1,4-conjugate addition (Michael addition), placing a - CN group at the -position (C3 of the ring). Subsequent acidic hydrolysis ( H ₃ O ^+ , heat) converts the - CN gr

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