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JEE Advanced levelSingle correct optionDifficulty 3 of 3ap196

1-Methylcyclohexane-1,2-diol is warmed with dilute . Assume the tertiary carbocation forms first and that hydride migration is the preferred shift. The major carbonyl product is

  1. A1-cyclopentylethan-1-one
  2. B3-methylcyclohexan-1-one
  3. Ccycloheptanone
  4. D2-methylcyclohexan-1-one

Answer: D

The tertiary OH leaves to give the cation at C-1. The hydrogen on C-2 shifts to C-1, which leaves the oxygen on C-2 as a protonated carbonyl and keeps the six-membered ring. After deprotonation the product is 2-methylcyclohexan-1-one (the methyl is now on a CH next to C=O).
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