Benzene C6H6

1
Benzene C6H6
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Table of Contents

• Stats
• Structure
• Bonding
• Electronic Properties
• Reactions
• Nomenclature
• Industry
• Harmful Effects

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Statistics

• Discovered by Michael Faraday - 1825
• Most Basic Aromatic Molecule
• Colorless Liquid
• Boiling Point 80.08oC
• Melting Point 5.48oC
• Density .880 g/cm3

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Statistics - continued

• Insoluble in Water
• Soluble in Oils Fats
• Explosive Vapors
• Flammable Liquid

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Structure

• Flat Structure
• Carbon Atoms are sp2 Hybridized
• Carbon has Triangular Planar Geometry

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Bonding

• Sigma and pi Bonding between Carbon atoms
• Has Resonance Structure gt
• Actual Bonds are All Intermediate Length
• Increased Stability

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Electronic Properties

• The Six Electrons in the pi Bonds are Loosely
  Held Compared to the Electrons in the sigma Bonds
• Those Six Electrons are Delocalized
• This causes a cloud of electrons above and below
  the plane of the benzene molecule

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Reactions

• The Resonance Structures of Benzene Increase its
  Stability
• Resist Addition Reactions Because That Would
  Destroy the Ring Structure
• Often Undergoes Substitution Reactions
• Benzene Serves as a Source of Electrons for
  Electrophilic Reagents

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Reactions - Types of Substitutions

• Nitration C6H6 HNO3 C6H6NO2 H2O
• Halogenation Carbon Replaced by Halogen
• Sulfonation Carbon Replaced by Sulfer
• Friedel-crafts Acyl group (RCO-) Attaches to
  Ring to Make a Keytone

Nitrobenzene
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Nomenclature of Benzene

• When Substituent Takes its Place in the Ring the
  New Molecules name is the prefix -benzene
• Ex Chlorobenzene

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Nomenclature - Continued

• If More Than One Group Attaches to Benzene then
  Positions Must be Indicated
• Ortho (?) One Space
• Meta (m) Two Spaces
• Para (p) Three Spaces

CH3
NO2
?-Nitrotoluene
NO2
Cl
M-Chloronitrobenzene
I
p-Bromoiodobenzene
Br
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Nomenclature - continued

• ?-Nitrotoluene
• m-Chloronitrobenzene
• p-Bromoiodobenzene

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Nomenclature - continued

• If 3 or More Groups Attach
• Numbers are Used to Indicate Positions
• 2-Chloro-4-nitrophenol

OH
Cl
1
2
6
3
5
4
NO2
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Industry

• Made from Coal Tar (a liquid left over when coal
  is heated) and Petroleum
• Used as a Source for Almost all Aromatic
  Compounds
• Make Complicated Aromatic Compounds by Taking
  Benzene and Add on Other Rings Piece by Piece

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Industry - continued

• Solvent for
• Sulfur, Phosphorus and Iodine
• Gums
• Fats, Waxes and Resins
• Simple Organic Compounds
• One of the Most Commonly Used Solvents in Organic
  Chemistry

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Industry - continued

• Can Make Aniline and Phenol

• Phenol
• Disinfectant
• Antiseptic (Diluted)
• Insecticide
• Explosives
• Detergent
• Raw Material for Aspirin

• Aniline
• Dye (Aniline Oil)
• Plastics
• Drugs (Sulfanilamide)
• Explosives

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Industry - continued

• Makes Toluene, a component of TNT
  (Trinitrotoluene)
• Makes Tear Gas
• Makes Acetone

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Toxic Nature

• Carcinogen -- Causes Leukemia
• Makes Dioxins
• Two Phenols Combine and Cl Connects to Make
  Chlorinated Dibenzo-p-dioxin
• Does not Dissolve in Water, but does in Oils and
  Fats
• Accumulates in the Food Web
• Mimics Hormones
• Disrupts Normal Functions and Growth