Alkene Reactions (General)

Hydrohalogenation

• H-X

• Intermediate: Carbocation

• H on less substituted C

• X on more substituted C

• Regioselectivity: Markovnikov

• Can be affected by rearrangements (methyl, hydride)

• Product: Alkyl Halide

Halogenation

• X-X (X₂)

• Intermediate: Halocyclic

• Anti-addition/trans

• Regioselectivity: N/A

• Product: Dihalide

Halohydrin

• H2O-X₂

• Intermediate: Halocyclic

• Anti-addition

• Regioselectivity: Markovnikov

• Product: Halohydrin

Acid catalyzed hydration

• H₂O, acid catalyst (H3PO4)

• Intermediate: Carbocation

• H on less substituted C

• OH on more substituted C

• Regioselectivity: Markovnikov

• Can be affected by rearrangements (methyl, hydride) BEFORE H2O attacks

• Product: Alcohol

Oxymercuration-demercuration

1. Hg(OAc), H2O

2. NaBH₄

• Hg is similar to halogenation step

• H2O gets double whammied into OH

• An H from 2. replaces Hg

• Regioselectivity: Markovnikov

• Product: Alkyl Halide

Hydroboration-oxidation

1. BH3, THF

2. H2O2, OH^-

• Intermediate: Organoborane

• Syn-addition

• Regioselectivity: Anti-Markovnikov

  • H on more substituted C, OH on less substituted C

• Product: Alcohol

Catalytic Hydrogenation

• H₂, Pt/Pd

• Syn-addition

• Only for alkenes/alkynes

• Product: Alkane

Epoxidation (mCPBA)

• mCPBA (RCOOOH)

• C-O bonds on same face (wedge OR dash)

• Oxygen connected by both C’s

• Product: Epoxide

Dihydroxylation

• H₃O⁺ attacks epoxide

• O in epoxide gets H⁺, H₂O attacks carbocation

• Anti-addition

• Products: diol, alcohol, vicinal diol, 1,2-di-alcohol

Ozonolysis

1. O₃

2. Zn, H₃O⁺(reductive) / KMnO₄ (oxidative)

• Cleaves through alkene bond, adding O to both double bond ends (C=O x2)

• Oxidative has an extra CO₂ at end

• BOTH have ketones at end

• Reductive has aldehyde

• Oxidative had carboxylic acid

• Regioselectivity: N/A

• Stereoselectivity: N/A

Cyclopropanation (Carbene)

• Carbene: R₂C

• CHCl₃, KOH

• Syn-addition

• Product: Cyclopropane