exam 3

• electrophilic addition rxns of alkenes:

  1. HX addition to alkenes
  2. acid catalyzed addition of H,OH
  3. addition of Br2, Cl2
  4. addition of Br2, Cl2 in H2O
  5. oxymercuration-demuraration/reduction
• HX addition to alkenes

  • regioselective rxn: makes most substituted alkyl halide (markovnikov)
  • carbonation intmd (3>2>1) --> alkyl groups e-donors via hyperconjugation
  • carbocations can rearrange to form more stable carbocations
• Acid catalyzed addition of H,OH

  • makes markivnikov alcohol (most substituted)
  • rxn is acid catalyzed (H3O+ in aq medium)
  • carbonation intmd --> rearrangement possible
• addition of Br2/Cl2

  • makes vicinal dihalides
  • stereoselective but not regioselective
  • no cis-siomer --> uses anti-addition )opposite sides of pi bond)
  • forms bromonium (choronium) cation intmd --> has extra bond which is more stable
  • rxn needs CHCl3 (chloroform) as catalyst
• addition of Br2/Cl2 in H2O

  • makes halohydrin
  • anti-addition of Br,OH/Cl,OH --> steroselective
  • regioselective rxn that forms most substituted alcohol
  • bromonium cation intmd
• oxymercuration-demuraration/reduction

  • 2 sequential rxns --> organomercury compound formed in 1st step
  • markovnikov addition of H,OH w/ no rearrangement (no carbonation)
  • mercurinium cation intmd