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JEE Main levelSingle correct optionDifficulty 2 of 3hc064

cis-But-2-ene is treated with cold, dilute, alkaline . The product is

  1. Abutane-1,2-diol
  2. Bbutan-2-ol
  3. Cmeso-butane-2,3-diol
  4. Dracemic (2R,3R)/(2S,3S)-butane-2,3-diol

Answer: C

Cold alkaline permanganate adds two OH groups to the same face of the double bond (syn addition). Syn addition to a cis-alkene with identical substituents on each carbon gives the meso diol. Syn addition to the trans-alkene would give the racemic pair.
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