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JEE MainChemistryAlcohols Phenols and Ethers

An alcohol, 3,3-dimethylbutan-2-ol, is subjected to the following reaction sequence: (i) Conc. H ₂ SO ₄ , (ii) O ₃ , Zn/H ₂ O The major final product(s) of this sequence is/are:

Options

  1. APropan-2-one
  2. B2,2-Dimethylpropanal and methanal
  3. C3-Methylbutan-2-one and methanal
  4. D2-Methylpropanal and ethanal

Correct answer

A. Propan-2-one

Step-by-step solution

In the first step, 3,3-dimethylbutan-2-ol undergoes acid-catalyzed dehydration. Protonation and loss of water form a secondary carbocation: CH ₃- C ( CH ₃)₂- CH ^+- CH ₃ . This secondary carbocation undergoes a 1,2-methyl shift from the adjacent quaternary carbon to form a more stable tertiary carbocation: CH ₃- C ^+( CH ₃)- CH ( CH ₃)- CH ₃ . According to Zaitsev's rule, elimination of a proton occurs from the adjacent carbon that yields the most substituted alkene. Deprotonation from C3 gives 2,3-dimethylbut-2-en

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