Alkanes and Aromatic Compounds

Contributed by:

Jonathan James Mon, Jan 17, 2022 06:01 PM UTC

The highlights are:
1. Organic chemistry and biochemistry
2. Alkanes
3. Alkenes and alkynes
4. Aromatic hydrocarbons
5. Hydrocarbon derivatives
6. Polymers
7. Natural Polymers

1. Chapter 22
Organic and
Biological Molecules

2. AP Chemistry
 LO 2.15 The student is able to explain observations regarding the solubility of
ionic solids and molecules in water and other solvents on the basis of particle
views that include intermolecular interactions and entropic effects.
(Sec 22.5-22.6)
 LO 5.11 The student is able to identify the noncovalent interactions within and
between large molecules, and/or connect the shape and function of the large
molecule to the presence and magnitude of these interactions. (Sec 22.6)

3. Chapter 22
Organic Chemistry and Biochemistry
 Organic Chemistry
 The study of carbon-containing compounds and their
properties. The vast majority of organic compounds
contain chains or rings of carbon atoms.
 Biochemistry
 The study of the chemistry of living things.
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4. Section 22.1
Alkanes: Saturated Hydrocarbons
 Compounds composed of carbon and hydrogen.
 Saturated: C—C bonds are all single bonds.
alkanes [CnH2n+2]
H H
H C C H
H H
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5. Section 22.1
Alkanes: Saturated Hydrocarbons
 Unsaturated: contains carbon–carbon multiple
bonds.
H H H H
H C C C H C C C H
H H H

6. Section 22.1
Alkanes: Saturated Hydrocarbons
Isomerism in Alkanes
 Structural isomerism – occurs when two molecules
have the same atoms but different bonds.
 Butane and all succeeding members of the
alkanes exhibit structural isomerism.
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7. Section 22.1
Alkanes: Saturated Hydrocarbons
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8. Section 22.1
Alkanes: Saturated Hydrocarbons
Rules for Naming Alkanes
1. For alkanes beyond butane, add –ane to the Greek
root for the number of carbons.
CH3–CH2–CH2–CH2–CH2–CH3 = hexane
2. Alkyl substituents: drop the –ane and add –yl.
C2H6 is ethane
C2H5 is ethyl
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9. Section 22.1
Alkanes: Saturated Hydrocarbons
Rules for Naming Alkanes
3. Positions of substituent groups are specified by
numbering the longest chain sequentially. The
numbering is such that substituents are at lowest
possible number along chain.
CH3
CH3–CH2–CH–CH2–CH2–CH3
1 2 3 4 5 6
3-methylhexane
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10. Section 22.1
Alkanes: Saturated Hydrocarbons
Rules for Naming Alkanes
4. Location and name are followed by root alkane
name. Substituents in alphabetical order and use
di–, tri–, etc.
CH3 CH3
CH3–CH2–CH–CH–CH2–CH3
1 2 3 4 5 6
3,4-dimethylhexane
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11. Section 22.1
Alkanes: Saturated Hydrocarbons
First Ten Normal Alkanes
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12. Section 22.1
Alkanes: Saturated Hydrocarbons
The Most Common Alkyl
Substituents and Their

13. Section 22.1
Alkanes: Saturated Hydrocarbons
EXERCISE!
Name each of the following:
CH3 CH3
a)
H3C C CH2 CH CH2 CH3
CH3 CH3
2,2,4,5-tetramethylhexane
CH2 CH3 CH2 CH3
b)
H3C C CH2 CH2 CH CH2 CH3
CH2 CH3
3,6-diethyl-3-methyloctane
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14. Section 22.1
Alkanes: Saturated Hydrocarbons
Combustion Reactions of Alkanes
 At a high temperature, alkanes react vigorously and
exothermically with oxygen.
 Basis for use as fuels.
2C4H10 (g ) + 13O2 (g )  8CO2 (g ) + 10H2O(g )
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15. Section 22.1
Alkanes: Saturated Hydrocarbons
Substitution Reactions of Alkanes
 Primarily where halogen atoms replace hydrogen
atoms.
hv
CH4 + Cl2   CH3Cl + HCl
hv
CH3Cl + Cl2   CH2Cl2 + HCl
hv
CH2Cl2 + Cl2   CHCl3 + HCl
hv
CHCl3 + Cl2   CCl4 + HCl
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16. Section 22.1
Alkanes: Saturated Hydrocarbons
Dehydrogenation Reactions of Alkanes
 Hydrogen atoms are removed and the product is an
unsaturated hydrocarbon.
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17. Section 22.1
Alkanes: Saturated Hydrocarbons
Cyclic Alkanes
 Carbon atoms can form rings containing only C—C
single bonds.
 General formula: CnH2n
C3H6 C4H8 C6H12
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18. Section 22.1
Alkanes: Saturated Hydrocarbons
The Chair and Boat Forms of Cyclohexane
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19. Section 22.2
Alkenes and Alkynes
 Alkenes: hydrocarbons that contain at least one carbon–
carbon double bond. [CnH2n]
CH3–CH=CH2 propene
 Alkynes: hydrocarbons containing at least one carbon–
carbon triple bond. [CnHn]
CH3–CH2–CΞC–CH3 2–pentyne

20. Section 22.2
Alkenes and Alkynes
Rules for Naming Alkenes
1. Root hydrocarbon name ends in –ene.
C2H4 is ethene
2. With more than 3 carbons, double bond is indicated by
the lowest–numbered carbon atom in the bond.
CH2=CH–CH2–CH3
1 2 3 4
1–butene
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21. Section 22.2
Alkenes and Alkynes
Rules for Naming Alkynes
 Same as for alkenes except use –yne as suffix.
CH3–CH2–CΞC–CH2–CH2–CH2–CH3
3–octyne
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22. Section 22.2
Alkenes and Alkynes
EXERCISE!
Name each of the following:
CH3 CH3
a) H3C CH CH2 C C CH3
CH3
2,3,5-trimethyl-2-hexene
b) CH2 CH3 CH2 CH3
H3C C CH CH2 CH CH2 CH3
6-ethyl-3-methyl-3-octene
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23. Section 22.2
Alkenes and Alkynes
Addition Reactions
 Pi Bonds (which are weaker than the C—C bonds),
are broken, and new  bonds are formed to the 
atoms being added.
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25. Section 22.3
Aromatic Hydrocarbons
 A special class of cyclic unsaturated hydrocarbons.
 Simplest of these is benzene (C6H6).
 The delocalization of the  electrons makes the benzene
ring behave differently from a typical unsaturated
hydrocarbon.
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26. Section 22.3
Aromatic Hydrocarbons
Benzene (Aromatic Hydrocarbon)

27. Section 22.3
Aromatic Hydrocarbons
 Unsaturated hydrocarbons generally undergo rapid
addition reactions, but benzene does not.
 Benzene undergoes substitution reactions in which
hydrogen atoms are replaced by other atoms.
Benzene
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29. Section 22.4
Hydrocarbon Derivatives
AP Learning Objectives, Margin Notes and References
 AP Margin Notes
 Acids and bases can serve as catalysts in chemical reactions. See Appendix 7.9 “Acid Catalysis” to learn more about
this acid-catalyzed reaction mechanism.

30. Section 22.4
Hydrocarbon Derivatives
 Molecules that are fundamentally hydrocarbons but
have additional atoms or groups of atoms called
functional groups.
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32. Section 22.5
AP Learning Objectives, Margin Notes and References
 Learning Objectives
 LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water
and other solvents on the basis of particle views that include intermolecular interactions and entropic effects.

35. Section 22.5
Types of Polymerization
 Addition Polymerization
 Monomers “add
together” to form the
polymer, with no other
products. (Teflon®)

36. Section 22.5
Types of Polymerization
 Condensation Polymerization
 A small molecule, such as water, is formed for each
extension of the polymer chain. (Nylon)
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37. Section 22.6
Natural Polymers
AP Learning Objectives, Margin Notes and References
 Learning Objectives
 LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water
and other solvents on the basis of particle views that include intermolecular interactions and entropic effects.
 LO 5.11 The student is able to identify the noncovalent interactions within and between large molecules, and/or
connect the shape and function of the large molecule to the presence and magnitude of these interactions.

38. Section 22.6
Natural Polymers
Proteins
 Natural polymers made up of -amino acids with molar
masses:
~ 6000 to > 1,000,000 g/mol
 Fibrous Proteins: provide structural integrity and
strength to muscle, hair and cartilage.
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39. Section 22.6
Natural Polymers
Proteins
 Globular Proteins:
 Roughly spherical shape
 Transport and store oxygen and nutrients
 Act as catalysts
 Fight invasion by foreign objects
 Participate in the body’s regulatory system
 Transport electrons in metabolism
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40. Section 22.6
Natural Polymers
α-Amino Acids
 –NH2 always attached to the α-carbon
(the carbon attached to –COOH)
H
C = α-carbon
R = side chains H2N C COOH
R
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42. Section 22.6
Natural Polymers
Levels of Structure in Proteins
 Primary: Sequence of amino acids in the protein chain.
 Secondary: The arrangement of the protein chain in the
long molecule (hydrogen bonding determines this).
 Tertiary: The overall shape of the protein (determined
by hydrogen-bonding, dipole-dipole interactions, ionic
bonds, covalent bonds and London forces).
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43. Section 22.6
Natural Polymers
Hydrogen Bonding in α-
Helical Arrangement of a
Protein Chain

45. Section 22.6
Natural Polymers
Carbohydrates
 Food source for most organisms and structural material
for plants.
 Empirical formula = CH2O
 Monosaccharides (simple sugars)
pentoses – ribose, arabinose
hexoses – fructose, glucose
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47. Section 22.6
Natural Polymers
Carbohydrates
 Disaccharides (formed from 2 monosaccharides joined
by a glycoside linkage, a C—O—C bond between the
rings):
sucrose (glucose + fructose)
 Polysaccharides (many monosaccharide units):
starch, cellulose
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49. Section 22.6
Natural Polymers
Nucleic Acids
 DNA (deoxyribonucleic acid): stores and transmits
genetic information, responsible (with RNA) for protein
synthesis.
(Molar masses = several billion)
 RNA (ribonucleic acid): helps in protein synthesis.
(Molar masses from 20,000 to 40,000 g/mol)
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50. Section 22.6
Natural Polymers
Nucleotides
 Monomers of the nucleic acids.
 Three distinct parts:
 A five–carbon sugar, deoxyribose in DNA and ribose
in RNA.
 A nitrogen–containing organic base.
 A phosphoric acid molecule (H3PO4).
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53. Section 22.6
Natural Polymers
DNA
 Key to DNA’s functioning is its double-helical structure
with complementary bases on the two strands.
 The bases form hydrogen bonds to each other.
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