1. CH 8-3: Electrophilic Addition of Br2 and Cl2
(1) Electrophilic Addition of HX (HCl & HBr) -Carbocation mechanism -Regioselective: Markovnikov’s Rule -Non-stereospecific reaction -Rearrangements possible
(2) Electrophilic Addition of H2O and ROH -Acid catalysis -Carbocation mechanism -Rearrangements possible
(3) Electrophilic Addition of Br2 and Cl2 to alkenes -”Halonium ion” mechanism -No carbocation!!! -Stereospecific reaction – Anti-Addition

2. Electrophilic Addition of Br2 or Cl2 to Alkenes
Part I: Dihalide Products (no other nucleophile)
Stereospecific Anti-Addition of Electrophile and Nucleophile

3. Electrophilic Addition of Br2 or Cl2 to Alkenes
The mechanism for halogen addition involves a new intermediate, the “halonium ion” (no carbocation):
bromonium ion
Since there is no carbocation, there are no rearrangements!

4. Electrophilic Addition of Br2 or Cl2 to Alkenes
The mechanism for halogen addition involves a new intermediate, the “halonium ion” (no carbocation):
The nucleophile must add anti = stereospecific.

5. Electrophilic Addition of Br2 or Cl2 to Alkenes
Part II: “Second” Nucleophile
Anti-Addition of electrophile and a second nucleophile.