23 April 2001Miles Selvidge1 Benzene C6H

23 April 2001Miles Selvidge2 Table of Contents b Stats b Structure b Bonding b Electronic Properties b Reactions b Nomenclature b Industry b Harmful Effects

23 April 2001Miles Selvidge3 Statistics b Discovered by Michael Faraday b Most Basic Aromatic Molecule b Colorless Liquid b Boiling Point: o C b Melting Point: 5.48 o C b Density:.880 g/cm 3

23 April 2001Miles Selvidge4 Statistics - continued b Insoluble in Water b Soluble in Oils & Fats b Explosive Vapors b Flammable Liquid

23 April 2001Miles Selvidge5 Structure b Flat Structure b Carbon Atoms are sp 2 Hybridized b Carbon has Triangular Planar Geometry

23 April 2001Miles Selvidge6 Bonding b Sigma and pi Bonding between Carbon atoms b Has Resonance Structure ==> b Actual Bonds are All Intermediate Length b Increased Stability

23 April 2001Miles Selvidge7 Electronic Properties b The Six Electrons in the pi Bonds are Loosely Held Compared to the Electrons in the sigma Bonds b Those Six Electrons are Delocalized This causes a cloud of electrons above and below the plane of the benzene moleculeThis causes a cloud of electrons above and below the plane of the benzene molecule

23 April 2001Miles Selvidge8 Reactions b The Resonance Structures of Benzene Increase its Stability Resist Addition Reactions Because That Would Destroy the Ring StructureResist Addition Reactions Because That Would Destroy the Ring Structure Often Undergoes Substitution ReactionsOften Undergoes Substitution Reactions b Benzene Serves as a Source of Electrons for Electrophilic Reagents

23 April 2001Miles Selvidge9 Reactions - Types of Substitutions b Nitration: C 6 H 6 + HNO 3 C 6 H 6 NO 2 + H 2 O b Halogenation: Carbon Replaced by Halogen b Sulfonation: Carbon Replaced by Sulfer b Friedel-crafts: Acyl group (RCO-) Attaches to Ring to Make a Keytone Nitrobenzene

23 April 2001Miles Selvidge10 Nomenclature of Benzene b When Substituent Takes its Place in the Ring the New Molecule’s name is the prefix -benzene b Ex: Chlorobenzene

23 April 2001Miles Selvidge11 Nomenclature - Continued b If More Than One Group Attaches to Benzene then Positions Must be Indicated b Ortho (  ) = One Space b Meta (m) = Two Spaces b Para (p) = Three Spaces CH 3 NO 2 Cl I Br  - Nitrotoluene M - Chloronitrobenzene p-Bromoiodobenzene

23 April 2001Miles Selvidge12 Nomenclature - continued b  -Nitrotoluene b m-Chloronitrobenzene b p-Bromoiodobenzene

23 April 2001Miles Selvidge13 Nomenclature - continued b If 3 or More Groups Attach Numbers are Used to Indicate PositionsNumbers are Used to Indicate Positions 2-Chloro-4-nitrophenol2-Chloro-4-nitrophenol OH Cl NO

23 April 2001Miles Selvidge14 Industry b Made from Coal Tar (a liquid left over when coal is heated) and Petroleum b Used as a Source for Almost all Aromatic Compounds Make Complicated Aromatic Compounds by Taking Benzene and Add on Other Rings Piece by PieceMake Complicated Aromatic Compounds by Taking Benzene and Add on Other Rings Piece by Piece

23 April 2001Miles Selvidge15 Industry - continued b 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 Chemistry

23 April 2001Miles Selvidge16 Industry - continued b Aniline: Dye (Aniline Oil)Dye (Aniline Oil) PlasticsPlastics Drugs (Sulfanilamide)Drugs (Sulfanilamide) ExplosivesExplosives b Phenol: Disinfectant Antiseptic (Diluted) Insecticide Explosives Detergent Raw Material for Aspirin b Can Make Aniline and Phenol

23 April 2001Miles Selvidge17 Industry - continued b Makes Toluene, a component of TNT (Trinitrotoluene) b Makes Tear Gas b Makes Acetone

23 April 2001Miles Selvidge18 Toxic Nature b Carcinogen -- Causes Leukemia b Makes Dioxins Two Phenols Combine and Cl Connects to Make Chlorinated Dibenzo-p-dioxinTwo Phenols Combine and Cl Connects to Make Chlorinated Dibenzo-p-dioxin b Does not Dissolve in Water, but does in Oils and Fats Accumulates in the Food WebAccumulates in the Food Web b Mimics Hormones Disrupts Normal Functions and GrowthDisrupts Normal Functions and Growth