JEE Main · 2019 · Shift-IImediumGOC-113

Which of the following compounds will show the maximum 'enol' content?

General Organic Chemistry (GOC) · Class 11 · JEE Main Previous Year Question

Question

Which of the following compounds will show the maximum 'enol' content?

Options
  1. a

    \ceCH3COCH3\ce{CH3COCH3}

  2. b

    \ceCH3COCH2COCH3\ce{CH3COCH2COCH3}

  3. c

    \ceCH3COCH2COOC2H5\ce{CH3COCH2COOC2H5}

  4. d

    \ceCH3COCH2CONH2\ce{CH3COCH2CONH2}

Correct Answerb

\ceCH3COCH2COCH3\ce{CH3COCH2COCH3}

Detailed Solution

Step 1: Identifying Factors for Enol Stability

  • (A) Acetone: Very low enol content.
  • (B) Acetylacetone (2,4-pentanedione): The enol is stabilized by intramolecular hydrogen bonding and resonance conjugation (O=CC=COHO=C-C=C-OH). Typically 76%\sim 76\% in liquid phase.
  • (C) Ethyl acetoacetate: stabilized by H-bonding, but ester carbonyl is less prone to enolization than ketone carbonyl.
  • (D) Acetoacetamide: Amide group further reduces enol stability compared to ketones.

Step 2: Conclusion \ceCH3COCH2COCH3\ce{CH3COCH2COCH3} shows the highest enol content due to efficient H-bonding and conjugation.

Answer: (b) CH3COCH2COCH3\boxed{\text{Answer: (b) CH3COCH2COCH3}} image

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from General Organic Chemistry (GOC)) inside The Crucible, our adaptive practice platform.

Which of the following compounds will show the maximum 'enol' content? (JEE Main 2019) | Canvas Classes