The diol shown is heated with dilute $H X_{2} SO X_{4}$ . Which structure is the major organic product of the pinacol-pinacolone rearrangement?

AStructure A
BStructure B
CStructure C
DStructure D

Answer: A

The diol is 2,3-dimethylbutane-2,3-diol (pinacol). Protonation and loss of water give a tertiary cation; a methyl group then shifts from the neighbouring carbinol carbon and the oxonium ion loses

H X^{+}

. The product is 3,3-dimethylbutan-2-one (pinacolone),

CH X_{3} COC (CH X_{3}) X_{3}

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The diol shown is heated with dilute HX2​SOX4​. Which structure is the major organic product of the pinacol-pinacolone rearrangement?

Answer: A

More questions on Pinacol rearrangement products of drawn diols

The diol shown is heated with dilute $H X_{2} SO X_{4}$ . Which structure is the major organic product of the pinacol-pinacolone rearrangement?