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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3o4015

Which of the following is/are correct for the heating of 2,2-dimethylpropan-1-ol (neopentyl alcohol) with concentrated ?

  1. ANo alkene can be formed without a skeletal rearrangement, since the carbon next to the carbinol carbon has no hydrogen.
  2. BA 1,2-methyl shift gives a tertiary carbocation.
  3. CThe major alkene is 2-methylbut-2-ene.
  4. DThe major alkene is 2-methylbut-1-ene because the reaction follows the Hofmann rule.

Answer: A, B, C

The carbinol carbon is attached to a quaternary carbon, so there is no beta-hydrogen and no alkene with the original skeleton can form. A 1,2-methyl shift gives the tertiary 2-methylbutan-2-yl cation, which loses H mainly from the CH2 group giving 2-methylbut-2-ene (Saytzeff). 2-methylbut-1-ene is only minor.
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