JEE Main · 2023 · Shift-IeasyHC-040

The two products formed in above reaction are:

Hydrocarbons · Class 11 · JEE Main Previous Year Question

Question

image The two products formed in above reaction are:

Options
  1. a

    Butanoic acid and acetic acid

  2. b

    Butanal and acetic acid

  3. c

    Butanal and acetaldehyde

  4. d

    Butanoic acid and acetaldehyde

Correct Answera

Butanoic acid and acetic acid

Detailed Solution

image Step 1: Draw 2-hexene

2-Hexene: \ceCH3CH=CHCH2CH2CH3\ce{CH3-CH=CH-CH2-CH2-CH3}

The double bond is between C2 and C3.

Step 2: Apply ozonolysis conditions

The reagents are: (i) \ceO3\ce{O3} (ii) \ceH2O\ce{H2O}

\ceH2O\ce{H2O} workup is oxidative (no \ceZn\ce{Zn} added) → this is oxidative ozonolysis. Oxidative workup conditions (\ceO3/H2O\ce{O3/H2O} or \ceO3/H2O2\ce{O3/H2O2}) convert:

  • \ceRCH=\ce{R-CH=}\ceRCOOH\ce{R-COOH} (carboxylic acid)
  • \ceRCR=\ce{R-CR'=}\ceRCOR\ce{R-CO-R'} (ketone, if no H on carbon)

Step 3: Identify the products

Cleavage of \ceCH3CH=CHCH2CH2CH3\ce{CH3-CH=CH-CH2CH2CH3} at C2=C3:

  • C2 fragment (\ceCH3CH=\ce{CH3-CH=}) → \ceCH3COOH\ce{CH3COOH} (acetic acid)
  • C3 fragment (\ce=CHCH2CH2CH3\ce{=CH-CH2CH2CH3}) → \ceCH3CH2CH2COOH\ce{CH3CH2CH2COOH} (butanoic acid)

Answer: Option (a) — Butanoic acid and acetic acid

Key Points to Remember:

  • Oxidative ozonolysis (\ceO3\ce{O3} + \ceH2O\ce{H2O} or \ceH2O2\ce{H2O2}): \ceCH=\ce{-CH=}\ceCOOH\ce{-COOH}
  • Reductive ozonolysis (\ceO3\ce{O3} + \ceZn/H2O\ce{Zn/H2O}): \ceCH=\ce{-CH=}\ceCHO\ce{-CHO}
  • 2-Hexene cleaves between C2 and C3 giving \ceC2\ce{C2} acid (acetic) + \ceC4\ce{C4} acid (butanoic)

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