Electrophilic Addition of Alkenes and Alkynes

• Reactions of electrophilic addition of alkenes

  • Hydration
  • Ether formation
  • Hydrohalogenation or Hydrogen acids
  • Halogenation
  • Halohydrin formation
  • Hydrogenation (or Reduction)
  • Epoxidation
  • Oxidation reaction
  • Ozonolysis
  • Polymerization
• Hydration


  1. Reactant: Addition of H2O

  2. Catalyst: Acidic catalysts (e.g., H3PO4, HCl, H2SO4 and H+)

  3. Product: Adds ROH (alcohol) on the secondary carbon/s

  4. Follows Markovnikov's Rule
• Types of hydration


  • Oxymercuration-Demercuration
  • Hydroboration
  • Enzymatic Hydration
• Ether formation


  1. Reactant: Addition of ROH/ alcohol

  2. Catalyst: Acid catalysts (H+)

  3. Product: Ether product

  4. Follows Markovnikov's Rule
• Hydrohalogenation or Hydrogen acids


  1. Reactant: Addition of HX (hydrogen halide)

  2. Catalyst: Ether

  3. Product: Monohalogenated alkene

  4. Follows Markovnikov's Rule
• Halogenation


  1. Reactant: Addition of X2 (halogens)

  2. Catalyst: DCM or CCl4

  3. Product: Dihalogenated alkenes

  4. Follows a trans orientation (anti-stereochemistry)

  5. Follows Markovnikov's Rule except for Br2
• Halohydrin formation


  1. Reactant: Addition of X2 (halogens) in H2O

  2. Catalyst: Any F, Cl, Br, I and H2O

  3. Product: Halohydrin (There's X and OH)

  4. Follows a trans orientation (anti-stereochemistry)
• Hydrogenation (or Reduction)


  1. Reactant/Reagent: Addition of H2 (hydrogens)

  2. Catalyst: Pd/PtO2

  3. Follows a cis orientation (syn-stereochemistry)
• Epoxidation


  1. Reactant: Addition of Peracid/ Peroxy acid (RCOOOH)

  2. Reagent: mCPBA (meta-choloroperoxybenzoic acid)

  3. Follows a cis orientation (syn-stereochemistry)
• Types of oxidation reaction

  • Hydroxylation (mild oxidation)
  • Bond cleavage (strong oxidation)
• Hydroxylation (mild oxidation)


  1. Reactant/Reagent: KMnO4

  2. Catalyst: Basic Medium (e.g., H2O, NaOH)

  3. Follows a cis orientation (syn-stereochemistry)

  4. When water is added, there will be a product of vicinal diol
• Bond cleavage (strong oxidation)

  1. Reactant/Reagent: KMnO4

  2. Catalyst: Acidic Medium (e.g., H3O)

  3. Ketone for 2 oxidized bonds

  4. Aldehyde for 3 oxidized bonds

  5. Carbon dioxide for 4 oxidized bonds
• Ozonolysis


  1. Reactant: Addition of ozone (O3)

  2. Catalyst: Zn (metal)

  3. Product: Carbonyl
• Polymerization


  1. Reactant: Addition of radical

  2. Catalyst: BzO* (Benzyloxy radical)
• Reactions of electrophilic addition of alkynes

  • Hydrogenation
  • Hydrohalogenation
  • Halogenation
  • Hydration
  • Acetylide formation
• Hydrogenation


  1. Reactant: Addition of H2 (hydrogen)

  2. Catalyst: Pd/C that allows for a saturated product to form or Lindlar's catalyst that follows a cis-orientation

  3. 2 molecules of hydrogen (H2) turn alkynes into alkanes
• Hydrohalogenation


  1. Reactant: Addition of HX (hydrogen halide)

  2. Product: Monohalogenated alkene

  3. Excess (X'ss) HX can form geminal halides or dihalide alkanes
• Halogenation


  1. Reactant: Addition of X2 (halogens)

  2. Product: Dihalogenated alkenes

  3. Follows a trans orientation (anti-stereochemistry)

  4. Excess (X'ss) X2 can form tetrasubstituted alkyl halides
• Hydration


  1. Reactant: Addition of H2O (water)

  2. Catalyst: H2SO4 / HgSO4

  3. Product: Enol (alkene alcohol)

  4. Enol converts into ketone when following Markovnikov's rule

  5. Enol converts into aldehyde when following Non-Markovnikov's rule
• Acetylide formation


  1. Elongation of alkyne

  2. Catalyst: NaNH2 (Sodium amide) / RX (Alkyl halide)

  3. Product: Enol (alkene alcohol)

  4. Condition: Only possible with terminal alkynes