Chapter 10 Carbon: More Than Just Another Element

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Chapter 10Carbon More Than Just Another Element
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ORGANIC CHEMISTRY
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cinnamaldehyde
eugenol
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Types of Organic Compounds

• Vast majority of over 20 million known compounds
  are based on C organic compounds.
• Generally contain C and H other elements
• Great variety of compounds

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Isomerism

• Isomers have identical composition but different
  structures
• Two forms of isomerism
• Constitutional (or structural)
• Stereoisomerism
• Constitutional
• Same empirical formula but different atom-to-atom
  connections
• Stereoisomerism
• Same atom-to-atom connections but different
  arrangement in space.

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Structural Isomers
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Stereoisomers Geometric

• Geometric isomers can occur when there is a CC
  double bond.

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Stereoisomers Optical

• Optical isomers are molecules with
  non-superimposable mirror images.
• Such molecules are called CHIRAL
• Pairs of chiral molecules are enantiomers.
• Chiral molecules in solution can rotate the plane
  of plane polarized light.

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Chiral CompoundsPolarized Light
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Stereoisomers Isomers
Chirality generally occurs when a C atom has 4
different groups attached.
Lactic acid
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Stereoisomers Isomers
Lactic acid isomers are nonsuperimposable
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Chirality Handedness in Nature

• These molecules are non-superimposable mirror
  images.

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Chirality Handedness in Nature

• These amino acids are non-superimposable mirror
  images.

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Stereoisomers in Nature
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The egg cases of the whelk have a right-handed
twist.
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Hydrocarbons

• Compounds of C and H
• Subgroups
• Alkanes C-C single bonds
• Alkenes CC double bonds
• Alkynes carbon-carbon triple bonds
• Aromatic based on benzene

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Hydrocarbons

• Alkanes have the general formula CnH2n2
• CH4 methane
• C2H6 ethane
• C3H8 propane
• C4H10 butane
• C5H12 pentane

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Methane Hydrate, CH4(H2O)x
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Hydrocarbons Structural Isomerism
Isomers of C5H12?

• C5H12 has 3 structural isomers.
• C6H14 has 5
• C7H14 has 9

Note names of isomers
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Hydrocarbons Alkanes

• Alkanes are colorless gases, liquids, and solids
• Generally unreactive (but undergo combustion)
• Not polar (or low polarity) and so are not
  soluble in water.

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Hydrocarbons Cycloalkanes

• All compounds are flexible.
• Cyclohexane, C6H12, has interconverting chair
  and boat forms.

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Alkenes Compounds with CC Double Bonds

• How many isomers are possible for a compound with
  the formula C4H8?

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AlkenesMany Occur Naturally
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Reactions of AlkenesADDITION REACTIONS

• Alkenes are unsaturated more bonds can form to
  the C atoms
• Molecules such as Br2, H2, HCl, HBr, and H2O add
  to the double bond

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An Addition Reaction
Fat placed in Br2 vapor

• The fat in bacon is partially unsaturated. The
  fat adds Br2 to the CC bonds.
• Fats can be hydrogenated with H2.

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An Addition Reaction
Fat placed in Br2 vapor
PLAY MOVIE
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An Addition Reaction

• Fats can be hydrogenated with H2.

PLAY MOVIE
Peanut butter has partially hydrogenated
vegetable oil.
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Trans Fatty Acidstend to raise total blood
cholesterol
CH3(CH2)7CHCH(CH2)7CO2H
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Trans Fatty Acids
Food Percentages of Trans-Fatty Acids
Butter 3.6
Soft Margarine 5.2
Hard Margarine 12.4
Vegetable Oils, Including Safflower, Sunflower, and Soy 0
Beef burger, Fried or Grilled 0.8
Chocolate Cake with Icing 7.1
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Alkynes

• Alkynes have carbon-carbon triple bonds.
• C2H2 common name acetylene systematic name
  ethyne

Preparation CaC2(s) H2O(liq) --gt
C2H2 (g) Ca(OH)2(s) ?fHo(C2H2, g) 226.7
kJ/mol
?rH for C2H2 O2 1300 kJ/mol
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Aromatic Compounds

• Benzene, C6H6, in the top 25 chemicals produced
  in the U.S.
• Starting point for hundreds of other compounds.

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Resonance in Benzene

• C6H6 has two resonance structures with
  alternating double bonds.
• The p electrons are delocalized over the ring.

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Resonance in Benzene

• CC bond order is _______________
• CC single bond 154 pm CC bond 134 pm
• CC bonds in benzene 139 pm

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Bonding in Benzene
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Other Aromatic Hydrocarbons
Toluene
Naphthalene
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Benzene Derivatives
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Naming Benzene Derivatives
1,4-dimethylbenzene Common name Para-xylene
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Reactions of Aromatics

• Substitutions not additions are typical.

AlCl3 is a catalyst. Catalysts typically used in
aromatic substitutions.
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Functional Groups

• See Chemistry Now, Chapter 10

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Alcohols

• Characterized by OH group
• Name add ol to name of hydrocarbon

Methanol
Butanol
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Structures of Alcohols

• C3H5OH how many structural isomers?

Naming Add -ol to name of 3-C hydrocarbon.
Indicate position of OH with number.
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Alcohol Properties

• Alcohols are a derivative of water
• Many alcohols dissolve in water

Methanol dissolves in water.
Butanol is NOT soluble in water.
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Sterno

• Alcohols burn in air
• A mixture of ethanol calcium acetate STERNO

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GLYCOLSAlcohols with Two OH Groups
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Alcohol ReactionsScreen 11.6
PLAY MOVIE
PLAY MOVIE
Eliminationthe reverse of addition
Substitution
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TYPES OF ALCOHOLS
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More Alcohol Reactions
Ethanol is a PRIMARY ALCOHOL. It is oxidized to
an ALDEHYDE and then to an ACID.
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More Alcohol Reactions
SECONDARY ALCOHOLS are oxidized to KETONES and
reaction stops there.
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Sugars Related to Alcohols

• Sugars are carbohydrates, compounds with the
  formula Cx(H2O)y.

What is the difference between a and b D-glucose?
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Sucrose and Ribose
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Amines

• Alcohols are derivatives of H2O (ROH) and amines
  are derivatives of NH3.

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Amines

• Amines generally have terrible odors!

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Amines

• Amines, like NH3, are bases

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Amines

• Many natural products and drugs (such as nicotine
  and cocaine) are bases.

Nicotine
H
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Compounds with Carbonyl Group
Aldehyde
Carboxylic acid
Ketone
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Structures of Aldehydes
Odors from aldehydes and ketones
Cinnamaldehyde
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Carboxylic Acids
Acids are found in many natural substances
bread, fruits, milk, wine
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Carboxylic Acids
Formic acid, HCO2H, gives the sting to ants.
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Acids Alcohols --gt ESTERS
Esters have generally pleasant odors
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Acids Alcohols --gt ESTERS
One of the important reactions in nature!
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Acids Alcohols --gt ESTERS
Many fruits such as bananas and strawberries
contain esters.
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GlycerolAlcohol with 3 OH Groups
Combine this with long chain acids f ??? Fatty
acids f fats and oils
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Fats and Oils
R organic group with NO CC bonds C12 Lauric
acid C16 Palmitic acid C18 Stearic acid
R organic group WITH CC bonds C18 oleic acid
What is the functional group in a fat or oil?
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Fats and Oils
Fats with CC bonds are usually LIQUDS
Oleic acid a monounsaturated fatty acid
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Fats and Oils
Fats with saturated acids (no CC bonds) are
SOLIDS.
Saturated fats are more common in animals.
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Fats and Polar Bears

• Bears gorge on blubber in the winter.
• During the summer bears rely on stored fat for
  energy.
• Burn 1-1.5 kg of fat per day.
• Water for metabolism comes from fat burning.

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Trans Fatty Acids

• Oleic acid is a monounsaturated cis-fatty acid
• Trans fatty acids have deleterious health
  effects.
• Trans fatty acids raise plasma LDL cholesterol
  and lower HDL levels.

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Fats and Oils Saponification
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Acids Amines --gt AMIDES
N-methylacetamide
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Acids Amines --gt AMIDES
Acetaminophen Tylenol, Datril, Momentum, ...
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Alpha-Amino Acids
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Peptides and Proteins
H2O
Adding more peptide links ---gt PROTEIN
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Polymers

• Giant molecules made by joining many small
  molecules called monomers
• Average production is 150 kg per person annually
  in the U.S.

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Polymer Classifications

• Thermoplastics (polyethylene) soften and flow
  when heated
• Thermosetting plastics soft initially but set
  to solid when heated. Cannot be resoftened.
• Other classification plastics, fibers,
  elastomers, coatings, adhesives

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Polymer Preparation

• Addition polymers directly adding monomer units
  together
• Condensation polymers combining monomer units
  and splitting out a small water (water)

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Polyethylene Addition Polymer
Ethylene
Polyethylene
A polymer with a molar mass of 1e6 has about
360,000 units.
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Mechanism of Addition Polymerization
PLAY MOVIE
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Types of Polyethylene
Branched, low density PE, LDPE
Cross-linked PE, CLPE
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Types of Polyethylene
Table 10.12 others are PVC, acrylonitrile,
polypropylene, polymethyl methacrylate
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Polystyrene

• Polystyrene is nonpolar material and dissolves in
  organic solvents.
• PS foam is mostly air, and when it dissolves it
  collapses to a much smaller volume.

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Slime!
Slime is polyvinylalcohol cross-linked with boric
acid
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Bubble Gum!A copolymer
Styrene butadiene
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Condensation Polymers
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Polyesters, PET
Jackets made from recycled PET soda bottles
Soda bottles, mylar film.
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Polyesters Mechanism
PLAY MOVIE
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Polyamides Nylon
PLAY MOVIE
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Polyamides Nylon

• Each monomer has 6 C atoms in its chain.
• A polyamide link forms on elimination of HCl
• Result nylon 66
• Proteins are polyamides

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Polymer Recycling Symbols
LDPE Low density PE 0.910-0.925 g/cm3 HDPE
High density PE 0.941-0.965 PP
Polypropylene 0.90 V PVC (Vinyl chloride)
1.30-1.58