Benzene C 6 H 6

23 April 2001 Miles Selvidge 1

Benzene CBenzene C66HH66

02

-

3

23 April 2001 Miles Selvidge 2

Table of ContentsTable of Contents

StatsStats StructureStructure BondingBonding Electronic Electronic

PropertiesProperties ReactionsReactions NomenclatureNomenclature IndustryIndustry Harmful EffectsHarmful Effects

23 April 2001 Miles Selvidge 3

StatisticsStatistics

Discovered by Discovered by Michael Faraday - Michael Faraday - 18251825

Most Basic Aromatic Most Basic Aromatic MoleculeMolecule

Colorless LiquidColorless Liquid Boiling Point: Boiling Point:

80.0880.08ooCC Melting Point: 5.48Melting Point: 5.48ooCC Density: .880 g/cmDensity: .880 g/cm33

23 April 2001 Miles Selvidge 4

Statistics Statistics -- continuedcontinued

Insoluble in WaterInsoluble in Water Soluble in Oils & Soluble in Oils &

FatsFats Explosive VaporsExplosive Vapors Flammable LiquidFlammable Liquid

23 April 2001 Miles Selvidge 5

StructureStructure

Flat StructureFlat Structure

Carbon Atoms are Carbon Atoms are

spsp2 2 HybridizedHybridized

Carbon has Carbon has

Triangular Planar Triangular Planar

GeometryGeometry

23 April 2001 Miles Selvidge 6

BondingBonding

Sigma and pi Sigma and pi Bonding between Bonding between Carbon atomsCarbon atoms

Has Resonance Has Resonance Structure ==>Structure ==>

Actual Bonds are Actual Bonds are All Intermediate All Intermediate LengthLength

Increased StabilityIncreased Stability

23 April 2001 Miles Selvidge 7

Electronic PropertiesElectronic Properties

The Six Electrons in the The Six Electrons in the pipi Bonds are Loosely Bonds are Loosely Held Compared to the Held Compared to the Electrons in the Electrons in the sigmasigma BondsBonds

Those Six Electrons are Those Six Electrons are DelocalizedDelocalized• This causes a cloud This causes a cloud

of electrons above of electrons above and below the plane and below the plane of the benzene of the benzene moleculemolecule

23 April 2001 Miles Selvidge 8

ReactionsReactions

The Resonance Structures of Benzene The Resonance Structures of Benzene Increase its StabilityIncrease its Stability• Resist Addition Reactions Because That Resist Addition Reactions Because That

Would Destroy the Ring StructureWould Destroy the Ring Structure• Often Undergoes Substitution ReactionsOften Undergoes Substitution Reactions

Benzene Serves as a Source of Benzene Serves as a Source of Electrons for Electrophilic ReagentsElectrons for Electrophilic Reagents

23 April 2001 Miles Selvidge 9

Reactions Reactions - Types of - Types of SubstitutionsSubstitutions

Nitration:Nitration: C C66HH66 + HNO + HNO33 C C66HH66NONO22 + H + H22OO

Halogenation:Halogenation: Carbon Replaced by Halogen Carbon Replaced by Halogen

Sulfonation:Sulfonation: Carbon Replaced by Sulfer Carbon Replaced by Sulfer

Friedel-crafts:Friedel-crafts: Acyl group (RCO-) Attaches to Acyl group (RCO-) Attaches to

Ring to Make a KeytoneRing to Make a Keytone

Nitrobenzene

23 April 2001 Miles Selvidge 10

Nomenclature of BenzeneNomenclature of Benzene

When Substituent When Substituent Takes its Place in Takes its Place in the Ring the New the Ring the New Molecule’s name Molecule’s name is the is the prefixprefix - -benzenebenzene

Ex: Ex: ChlorobenzeneChlorobenzene

23 April 2001 Miles Selvidge 11

NomenclatureNomenclature - Continued- Continued

If More Than One Group Attaches If More Than One Group Attaches to Benzene then Positions Must be to Benzene then Positions Must be IndicatedIndicated

Ortho (Ortho () = One Space) = One Space

Meta (m) = Two SpacesMeta (m) = Two Spaces

Para (p) = Three SpacesPara (p) = Three Spaces

CH3NO2

NO2

Cl

I

Br

-Nitrotoluene

M-Chloronitrobenzene

p-Bromoiodobenzene

23 April 2001 Miles Selvidge 12

Nomenclature Nomenclature - continued- continued

-Nitrotoluene -Nitrotoluene

m-Chloronitrobenzenem-Chloronitrobenzene

p-Bromoiodobenzenep-Bromoiodobenzene

23 April 2001 Miles Selvidge 13

Nomenclature Nomenclature - continued- continued

If 3 or More Groups AttachIf 3 or More Groups Attach• Numbers are Used to Indicate Numbers are Used to Indicate

PositionsPositions

• 2-Chloro-4-nitrophenol2-Chloro-4-nitrophenolOH

Cl

NO2

12

34

5

6

23 April 2001 Miles Selvidge 14

IndustryIndustry

Made from Coal Tar (a liquid left over Made from Coal Tar (a liquid left over

when coal is heated) and Petroleumwhen coal is heated) and Petroleum

Used as a Source for Almost all Used as a Source for Almost all

Aromatic CompoundsAromatic Compounds• Make Complicated Aromatic Compounds Make Complicated Aromatic Compounds

by Taking Benzene and Add on Other by Taking Benzene and Add on Other Rings Piece by PieceRings Piece by Piece

23 April 2001 Miles Selvidge 15

Industry Industry - continued- continued

Solvent for:Solvent for:

• Sulfur, Phosphorus and IodineSulfur, Phosphorus and Iodine

• GumsGums

• Fats, Waxes and ResinsFats, Waxes and Resins

• Simple Organic CompoundsSimple Organic Compounds– One of the Most Commonly Used Solvents in Organic One of the Most Commonly Used Solvents in Organic

ChemistryChemistry

23 April 2001 Miles Selvidge 16

Industry Industry - continued- continued

Aniline: Aniline: • Dye (Aniline Oil)Dye (Aniline Oil)• PlasticsPlastics• Drugs Drugs

(Sulfanilamide) (Sulfanilamide) • ExplosivesExplosives

Phenol:Phenol:• DisinfectantDisinfectant• Antiseptic (Diluted)Antiseptic (Diluted)• InsecticideInsecticide• ExplosivesExplosives• DetergentDetergent• Raw Material for AspirinRaw Material for Aspirin

Can Make Aniline and PhenolCan Make Aniline and Phenol

23 April 2001 Miles Selvidge 17

Industry Industry - continued- continued

Makes Toluene, a component of Makes Toluene, a component of TNT (Trinitrotoluene)TNT (Trinitrotoluene)

Makes Tear GasMakes Tear Gas

Makes AcetoneMakes Acetone

23 April 2001 Miles Selvidge 18

Toxic NatureToxic Nature

Carcinogen -- Causes LeukemiaCarcinogen -- Causes Leukemia Makes DioxinsMakes Dioxins

• Two Phenols Combine and Cl Connects Two Phenols Combine and Cl Connects to Make Chlorinated Dibenzo-p-dioxinto Make Chlorinated Dibenzo-p-dioxin

Does not Dissolve in Water, but does Does not Dissolve in Water, but does in Oils and Fatsin Oils and Fats• Accumulates in the Food WebAccumulates in the Food Web

Mimics HormonesMimics Hormones• Disrupts Normal Functions and GrowthDisrupts Normal Functions and Growth