1. CH 8-1 Electrophilic Addition of HX
Chapter 8: Electrophilic Addition of an Electrophile (E+) and Nucleophile to Alkenes
CH 8-1 Electrophilic Addition of HX
(1) Electrophilic Addition of HX (HCl & HBr) -What is an “electrophile”? -Carbocation mechanism (rearrangements possible) -Regioselective: “Markovnikov’s Rule” -Non-stereospecific reaction
(2) Electrophilic Addition of H2O and ROH -Acid catalyzed -Carbocation mechanism (rearrangements possible)
(3) Electrophilic Addition of Br2 and Cl2 -”Halonium ion” mechanism -No carbocation -Stereospecific reaction

2. Electrophilic Addition of an Electrophile (E+) and Nucleophile to Alkenes
Electrophile (E+): an electron deficient atom (“Lewis Acid”)
E+ must have a d+ or full positive charge
E+ is always paired with a nucleophile (Nuc)
Alkene sp2 carbons labeled d- (least substituted) and d+ (most substituted)
Regioselective Reaction (Markovnikov Addition):
E+ is attracted to the d- carbon (pi electrons “grab” E+)
Nuc is attracted to and “grabs” the d+ carbon

3. Electrophilic Addition of an Electrophile (E+) and Nucleophile to Alkenes
(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

4. Electrophilic Addition of an Electrophile (E+) and Nucleophile to Alkenes
(1) Electrophilic Addition of HX (HCl & HBr) -Carbocation mechanism -Regioselective: Markovnikov’s Rule -Non-stereospecific reaction -Rearrangements possible

5. Electrophilic Addition of HX: non-Stereospecific
The electrophile adds randomly to either side of the double bond, and nucleophile to either side of carbocation:
Random addition produces all possible stereoisomers: in this case a Racemic Mixture of enantiomers (50:50 mix).