BENZENE

CHEM 40 | Basic Organic Chemistry

Halogenation

A halogen atom X (X = CI or Br) replaces an H atom of the aromatic ring

Halogenation

- Reagent: _____

CI₂ and Br₂

Halogenation

less reactive than alkenes

Halogenation

- Electrophile: _____

Halonium ion (X⁺)

Halogenation

- Catakysts: _____

FeBr₃ or FeCI₃

Halogenation

- Product: _____

Aryl Halides

Nitration

A nitro group (-NO₂) replaces an H atom of the aromatic ring

Nitration

- Reagent: _____

H₂SO₄

Nitration

- Electrophile: _____

Nitronium ion (NO₂⁺)

Sulfonation

A sulfo group (-SO₃H) replaces an H atom of the aromatic ring

Sulfonation

- Electrophile: _____

Sulfur trioxide (SO₃) or HSO₃⁺

Sulfonation

- Reagent: _____

fuming H₂SO₄

Friedel-Crafts Alkylation

ALKYLATION | Charles Friedel and James Crafts (1877)

Friedel-Crafts Alkylation

Transfer of an alkyl group R from one atom to another atom (alkylation)

Friedel-Crafts Alkylation

Treatment of benzene with anlkyl halide and lewis acid (AICI₃)

Friedel-Crafts Alkylation

forms a new C-C bond

Friedel-Crafts Alkylation

- Electrophile: _____

carbocation

Friedel-Crafts Alkylation

- Reagent: _____

two moles of AICI₃ per mole of benzene

Friedel-Crafts Acylation

ACYLATION | Charles Friedel and James Crafts (1877)

Friedel-Crafts Acylation

transfer of an acyl group from one atom to another atom (acylation)

Friedel-Crafts Acylation

treatment of benzene with an acid chloride and a lewis acid (AICI₃) to form a ketone

Friedel-Crafts Acylation

forms a new C-C bond

Friedel-Crafts Acylation

- Reagent: _____

two moles of AICI₃ per mole of benzene

Friedel-Crafts Acylation

- Electrophile: _____

acylium ion (R-C⁺=O)

Free-radical halogenation

The preferred site is the sp³-hybridized C atom right next to the benzene ring (known as the benzylic carbon)

Free-radical halogenation

- Reagent: _____

CI₂ | CCI₄, hv | Br₂ | CCI₄, hv

Free-radical halogenation

- Intermediate: _____

the resonance-stabilized benzylic free-radical

Oxidation

Arenes containing at least one benzylic H are oxidized with₄ to benzoic acid

Oxidation

- Reagent: _____

hot KMnO₄ and H⁺

Hydrogenation

Occurs rapidly in the side chain in the presence of ordinary catalysts

Hydrogenation

- Reagent: _____

H₂, Pd/C | x’s H₂ | high T and P Rh cat

Electrophilic Addition (Alkenylbenzene): Hydrohalogenation

- Reagent: _____

HBr

Electrophilic Addition (Alkenylbenzene): Hydrohalogenation

Electrophilic Addition (Alkenylbenzene): Hydration

Electrophilic Addition (Alkenylbenzene): Hydration

- Reagent: _____

aq. H₂SO₄ | HgSO₄

Reduction

The -NO₂ (nitro) group is converted to -NH₂ (amino) group using hydrogen and a metal catalyst

Reduction

- Reagent: _____

H₂, Pd/C | SmCI₂, H₃O⁺ and ^-OH | NaBH₄

Reduction

Reduction

Conversion of acylbenzes to alkybenzenes

Clemmensen Reduction

- Reagent: _____

Zn(Hg) | HCI, heat

Wolff-Kishner Reduction

- Reagent: _____

NH₂NH₂ | KOH, heat

Clemmensen Reduction

Wolff-Kishner Reduction

Alkali-fusion

conversion of benzenesulfonic acids to phenols

Alkali-fusion

- Reagent: _____

1. NaOH, 300 °C

2. H₃O⁺