Halohydrin Formation: Anti Addition via a Halonium Ion

Learn halohydrin formation from alkenes: halonium ion, anti addition, and why OH ends up on the more substituted carbon. Includes common distractors and practice.

  • Overall transformation: Alkene → halohydrin (X and OH added)
  • Reagents: X2 (Br2 or Cl2) in H2O (or NBS/H2O)
  • Key intermediate: Halonium ion (bridged)
  • Regiochemistry: OH goes to more substituted carbon
  • Stereochemistry: Anti addition (opening opposite the halogen bridge)
  • Exam type: Predict the major product
  • Exam type: Regiochemistry
  • Exam type: Stereochemistry

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