Chapter 22
Organic and
Biological Molecules
Chapter 22
Table of Contents
22.1
22.2
22.3
22.4
22.5
22.6
Alkanes: Saturated Hydrocarbons
Alkenes and Alkynes
Aromatic Hydrocarbons
Hydrocarbon Derivatives
Polymers
Natural Polymers
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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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Section 22.1
Alkanes: Saturated Hydrocarbons
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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Section 22.1
Alkanes: Saturated Hydrocarbons
Hydrocarbons
• Unsaturated: contains carbon–carbon multiple
bonds.
H
H
H
C
C
H
H
H
H
C
H
C
C
C H
H
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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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Section 22.1
Alkanes: Saturated Hydrocarbons
Butane
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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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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
3-methylhexane
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6
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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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Section 22.1
Alkanes: Saturated Hydrocarbons
First Ten Normal Alkanes
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Section 22.1
Alkanes: Saturated Hydrocarbons
The Most Common Alkyl Substituents and Their Names
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Section 22.1
Alkanes: Saturated Hydrocarbons
Exercise
Name each of the following:
CH3
a)
H3C C
CH3
CH2 CH
CH3
CH2
CH3
CH3
2,2,4,5-tetramethylhexane
b) H C
3
CH2 CH3
CH2 CH3
C
CH
CH2 CH2
CH2 CH3
CH2 CH3
3,6-diethyl-3-methyloctane
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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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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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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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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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Section 22.1
Alkanes: Saturated Hydrocarbons
The Chair and Boat Forms of Cyclohexane
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Section 22.2
Atomic Masses
Alkenes
and Alkynes
Hydrocarbons
• Alkenes: hydrocarbons that contain a carbon–
carbon double bond. [CnH2n]
CH3 CH=CH2
propene
• Alkynes: hydrocarbons containing a carbon–
carbon triple bond.
CH3 CH2 C C CH3
2–pentyne
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Section 22.2
Atomic Masses
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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Section 22.2
Atomic Masses
Alkenes
and Alkynes
Rules for Naming Alkynes
• Same as for alkenes except use –yne as suffix.
CH3 CH2 C C CH2 CH2 CH2 CH3
3–octyne
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Section 22.2
Atomic Masses
Alkenes
and Alkynes
Exercise
Name each of the following:
a)
CH3
CH3
H3C CH CH2 C
C
CH3
CH3
2,3,5-trimethyl-2-hexene
b)
CH2 CH3
H3C C
CH
CH2 CH3
CH2
CH
6-ethyl-3-methyl-3-octene
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CH2
CH3
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Section 22.2
Atomic Masses
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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Section 22.2
Atomic Masses
Alkenes
and Alkynes
Halogenation Reactions
• Addition of halogen atoms of alkenes and
alkynes.
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Section 22.3
The Mole Hydrocarbons
Aromatic
• 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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Section 22.3
The Mole Hydrocarbons
Aromatic
Benzene (Aromatic Hydrocarbon)
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Section 22.3
The Mole Hydrocarbons
Aromatic
•
•
Unsaturated hydrocarbons generally undergo rapid
addition reactions, but benzene does not.
Benzene undergoes substitution reactions in which
hydrogen atoms are replaced by other atoms.
Cl
FeCl3
+ Cl2 

Benzene
+ HCl
Chlorobenzene
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Section 22.3
The Mole Hydrocarbons
Aromatic
More Complex Aromatic Systems
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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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Section 22.4
Hydrocarbon Derivatives
The Common
Functional Groups
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Section 22.5
Polymers
• Large, usually chainlike molecules that are built
from small molecules called monomers.
Monomer
Ethylene
Vinyl chloride
Tetrafluoroethylene
Polymer
Polyethylene
Polyvinyl chloride
Teflon®
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Section 22.5
Polymers
Types of Polymerization
• Addition Polymerization
 Monomers “add together” to form the
polymer, with no other products. (Teflon®)
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Section 22.5
Polymers
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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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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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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Section 22.6
Natural Polymers
-Amino Acids
• –NH2 always attached to the -carbon
(the carbon attached to COOH)
C = -carbon
R = side chains
H
H2N C
COOH
R
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Section 22.6
Natural Polymers
Bonding in
H
-Amino Acids
H O H H
N C
H
R
C N C
O
C
R'
+ H2O
OH
A peptide linkage
• There are 20 amino acids commonly found in
proteins.
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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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Section 22.6
Natural Polymers
Hydrogen Bonding in
α-Helical Arrangement
of a Protein Chain
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Section 22.6
Natural Polymers
Pleated Sheet
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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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Section 22.6
Natural Polymers
Some Important Monosaccharides
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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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Section 22.6
Natural Polymers
The Disaccharide Sucrose is Formed From α-D-glucose and
Fructose
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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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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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Section 22.6
Natural Polymers
Deoxyribose (in DNA)
and Ribose (in RNA)
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Section 22.6
Natural Polymers
The Organic Bases Found in DNA and RNA
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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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Section 22.6
Natural Polymers
Hydrogen Bonding in DNA
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