1. Carbon: More than Just Another Element Lectures written by John Kotz
Chemistry and Chemical Reactivity 6th Edition
John C. Kotz Paul M. Treichel Gabriela C. Weaver
CHAPTER 11
Carbon: More than Just Another Element
Lectures written by John Kotz
© 2006 Brooks/Cole Thomson

2. ORGANIC CHEMISTRY

3. cinnamaldehyde
eugenol

4. 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

5. 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
Same atom-to-atom connections but different arrangement in space.

6. Structural Isomers

7. Stereoisomers: Geometric
Geometric isomers can occur when there is a C=C double bond.
Trans-2-butene
Cis-2-butene

8. 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.

9. Chiral Compounds—Polarized Light

10. Stereoisomers Isomers
Chirality generally occurs when a C atom has 4 different groups attached.
Lactic acid

11. Stereoisomers Isomers
Lactic acid isomers are nonsuperimposable

12. Chirality: Handedness in Nature
These molecules are non-superimposable mirror images.

13. Chirality: Handedness in Nature
These amino acids are non-superimposable mirror images.

14. Stereoisomers in Nature
Right- and left-handed seashells
The DNA here is right-handed

15. The egg cases of the whelk have a right-handed twist.

16. Hydrocarbons Compounds of C and H Subgroups: Alkanes: C-C single bonds
Alkenes: C=C double bonds
Alkynes: carbon-carbon triple bonds
Aromatic: based on benzene

17. Hydrocarbons Alkanes have the general formula CnH2n+2 CH4 = methane
C2H6 = ethane
C3H8 = propane
C4H10 = butane
C5H12 = pentane

19. Methane Hydrate, CH4(H2O)x

20. A colony of worms on an outcropping of methane hydrate on the ocean floor.
See the interchapter “The Chemistry of Fuels and Energy Sources”

21. Hydrocarbons & Structural Isomerism
Isomers of C5H12?
C5H12 has 3 structural isomers.
C6H14 has 5
C7H14 has 9
Note names of isomers

22. 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.

23. Hydrocarbons: Cycloalkanes
All compounds are flexible.
Cyclohexane, C6H12, has interconverting “chair” and “boat” forms.

24. Alkenes: Compounds with C=C Double Bonds
How many isomers are possible for a compound with the formula C4H8?

25. Alkenes— Many Occur Naturally

26. Reactions of Alkenes: ADDITION 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

27. An Addition Reaction
Fat placed in Br2 vapor
The fat in bacon is partially unsaturated. The fat adds Br2 to the C=C bonds.
Fats can be “hydrogenated” with H2.

28. An Addition Reaction
Fat placed in Br2 vapor

29. An Addition Reaction Fats can be “hydrogenated” with H2.
Peanut butter has partially hydrogenated vegetable oil.

30. Trans Fatty Acids tend to raise total blood cholesterol
CH3(CH2)7CH=CH(CH2)7CO2H
Trans Fatty Acids tend to raise total blood cholesterol

31. 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
Beefburger, Fried or Grilled
0.8
Chocolate Cake with Icing
7.1

32. Alkynes Alkynes have carbon-carbon triple bonds.
C2H2: common name = acetylene systematic name = ethyne
Preparation:
CaC2(s) + H2O(liq) --> C2H2 (g) + Ca(OH)2(s)
∆Hfo(C2H2, g) = kJ/mol
∆Hrxn for C2H2 + O = –1300 kJ/mol

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

34. Resonance in Benzene
C6H6 has two resonance structures with alternating double bonds.
The π electrons are delocalized over the ring.

35. Resonance in Benzene CC bond order is _______________
C–C single bond = 154 pm C=C bond = 134 pm
CC bonds in benzene = 139 pm
π electrons delocalized

36. Bonding in Benzene

37. Other Aromatic Hydrocarbons
Toluene
Naphthalene

38. Benzene Derivatives Aniline Phenol TNT trinitrotoluene C6H5NH2 C6H5OH
C6H4CH3(NO2)3

39. Naming Benzene Derivatives
1,4-dimethylbenzene
Common name: Para-xylene

40. Reactions of Aromatics
Substitutions — not additions — are typical.
AlCl3 is a catalyst. Catalysts typically used in aromatic substitutions.

41. Functional Groups
See CD-ROM Screens 11.5 & 11.6

42. Alcohols Characterized by –OH group
Name: add –ol to name of hydrocarbon
Methanol
Butanol

43. Structures of Alcohols
C3H5OH: how many structural isomers?
Naming: Add -ol to name of 3-C hydrocarbon. Indicate position of OH with number.

44. Alcohol Properties Alcohols are a derivative of water
Many alcohols dissolve in water
Methanol dissolves in water.
Butanol is NOT soluble in water.

45. “Sterno” Alcohols burn in air
A mixture of ethanol + calcium acetate = STERNO

46. GLYCOLS Alcohols with Two OH Groups
Propylene glycol
Ethylene glycol

47. Alcohol Reactions Screen 11.6
Substitution
Elimination—the reverse of addition

48. TYPES OF ALCOHOLS

49. More Alcohol Reactions
Ethanol is a PRIMARY ALCOHOL. It is oxidized to an ALDEHYDE and then to an ACID.

50. More Alcohol Reactions
SECONDARY ALCOHOLS are oxidized to KETONES — and reaction stops there.

51. Sugars: Related to Alcohols
Sugars are carbohydrates, compounds with the formula Cx(H2O)y.
What is the difference between a and b D-glucose?

52. Sucrose and Ribose
Deoxyribose, the sugar in the DNA backbone.

53. Amines
Alcohols are derivatives of H2O (R–OH) and amines are derivatives of NH3.
Trimethylamine
Dimethylamine
Methylamine

54. Amines generally have terrible odors!
Pyridine
Cadaverine

55. Amines, like NH3, are bases

56. Amines
Many natural products and drugs (such as nicotine and cocaine) are bases. H+
Nicotine

57. Compounds with Carbonyl Group
Aldehyde
Carboxylic acid
Ketone

58. Structures of Aldehydes
Cinnamaldehyde
Odors from aldehydes and ketones

59. Carboxylic acid group with acidic H+
Carboxylic Acids
Benzoic acid
Acetic acid
Carboxylic acid group with acidic H+
All are WEAK acids
Acids are found in many natural substances: bread, fruits, milk, wine

60. Formic acid, HCO2H, gives the sting to ants.
Carboxylic Acids
Aspirin, acetylsalicylic acid

61. Acids + Alcohols --> ESTERS
Esters have generally pleasant odors

62. Acids + Alcohols --> ESTERS
One of the important reactions in nature!

63. Acids + Alcohols --> ESTERS
Many fruits such as bananas and strawberries contain esters.

64. Glycerol Alcohol with 3 OH Groups
Combine this with long chain acids > ???
Fatty acids ---> fats and oils

65. Fats and Oils R = organic group with NO C=C bonds C12 = Lauric acid
C16 = Palmitic acid
C18 = Stearic acid
What is the functional group in a fat or oil?
R = organic group with C=C bonds
C18 = oleic acid

66. Fats with C=C bonds are usually LIQUDS
Fats and Oils
Fats with C=C bonds are usually LIQUDS
Oleic acid: a monounsaturated fatty acid
C=C bond

67. Fats and Oils Fats with saturated acids (no C=C bonds) are SOLIDS.
Saturated fats are more common in animals.

68. Fats and Polar Bears Bears gorge on blubber in the winter.
During the summer bears rely on stored fat for energy.
Burn kg of fat per day.
Water for metabolism comes from fat burning.

69. Trans Fatty Acids Oleic acid is a mono–unsaturated cis-fatty acid
Trans fatty acids have deleterious health effects.
Trans fatty acids raise plasma LDL cholesterol and lower HDL levels.
C=C bond

70. Fats and Oils: Saponification

71. Acids + Amines --> AMIDES
N-methylacetamide

72. Acids + Amines --> AMIDES
Acetoaminophen
Tylenol, Datril, Momentum, ...

73. Alpha-Amino Acids

74. Peptides and Proteins
– H2O
Adding more peptide links ---> PROTEIN

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

76. 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

77. Polymer Preparation
Addition polymers — directly adding monomer units together
Condensation polymers — combining monomer units and splitting out a small water (water)

78. Polyethylene: Addition Polymer
A polymer with a molar mass of 1e6 has about 360,000 units.

79. Mechanism of Addition Polymerization

80. Types of Polyethylene Linear, high density PE (HDPE)
Branched, low density PE, LDPE
Cross-linked PE, CLPE

81. Types of Polyethylene
Table 11.12: others are PVC, acrylonitrile, polypropylene, polymethyl methacrylate

82. 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.

83. Slime!
Slime is polyvinylalcohol cross-linked with boric acid

84. Bubble Gum! A copolymer
Styrene + butadiene

85. Condensation Polymers

86. Polyesters, PET Jackets made from recycled PET soda bottles
Soda bottles, mylar film.

87. Polyesters: Mechanism

88. Polyamides: Nylon

89. Polyamides: Nylon Each monomer has 6 C atoms in its chain.
A polyamide link forms on elmination of HCl
Result = nylon 66
Proteins are polyamides

90. Polymer Recycling Symbols
LDPE = Low density PE = g/cm3
HDPE = High density PE =
PP = Polypropylene = 0.90
V = PVC (Vinyl chloride) =