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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3o2218

3,3-Dimethylbut-1-ene reacts with (no peroxide). Which statements are correct?

  1. AA 1,2-methyl shift converts the first-formed secondary cation into a tertiary cation
  2. BThe major product is 2-bromo-2,3-dimethylbutane
  3. CThe minor unrearranged product, 2-bromo-3,3-dimethylbutane, contains a stereocentre
  4. DThe first-formed carbocation is primary

Answer: A, B, C

H+ adds to the terminal carbon, giving the secondary cation . Methyl migration gives the tertiary cation and the major product 2-bromo-2,3-dimethylbutane. The unrearranged has four different groups on C2, so it is chiral.
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