Alkenes

Formation of Alkenes by Dehydrohalogenation of Alkyl Halides

Base (NaOEt, KOH, or t-BuOK) in EtOH or DMSO; heat.

Dehydration of Alcohols

H₂SO₄ or H₃PO₄ / heat; water present; forms alkene.

H–X Addition

HBr (or HCl, HI) in CH₂Cl₂; Markovnikov addition.

H–Br Radical Addition

HBr + ROOR (peroxide); anti-Markovnikov addition.

Hydration of Alkenes

H₃O⁺ (dilute acid); aqueous solvent; Markovnikov alcohol.

Oxymercuration–Demercuration

Hg(OAc)₂/H₂O then NaBH₄; Markovnikov alcohol, anti addition.

Hydroboration–Oxidation

BH₃·THF then H₂O₂, NaOH; syn addition, anti-Markovnikov.

Halogen Addition (X₂ or X–Y)

Cl₂ or Br₂ in CCl₄ or CH₂Cl₂; anti addition; vicinal dihalide.

Halohydrin Formation

Cl₂ or Br₂ in H₂O; anti addition; OH on more substituted carbon.

Epoxidation Reaction (Peroxyacid)

mCPBA (or RCO₃H, MMPP) in CH₂Cl₂; syn addition; epoxide formation.

Acidic Epoxide Opening

H₃O⁺ (acidic water); OH adds to more substituted carbon; anti addition.

Basic Epoxide Opening

NaOH or other base in H₂O; OH adds to less substituted carbon; anti addition.

Syn Hydroxylation

cold dilute KMnO₄, then -OH with H2O; syn diol formation.

Oxidative Cleavage (Hot KMnO₄)

Hot concentrated KMnO₄ (acid conditions also help); cleaves C=C; forms carboxylic acids and ketones.

Basic Cyclization of a Halohydrin

Halohydrin + base (NaOH, 2,6-lutidine) in H₂O; intramolecular SN2 → epoxide; halogens: Cl, Br, I only.

Ozonolysis

O₃ then (CH₃)₂S; produces aldehydes and ketones.

Catalytic Hydrogenation (Alkene)

H₂ with Pt, Pd, or Ni catalyst; syn addition; converts alkene to alkane.