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23.1 Introduction to
Functional Groups
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Chapter 23
Functional Groups
23.1 Introduction to Functional
Groups
23.2 Alcohols, Ethers, and Amines
23.3 Carbonyl Compounds
23.4 Polymers
1
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23.1 Introduction to
Functional Groups
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CHEMISTRY
& YOU
How can you tell the difference between
one organic compound and another?
From a distance, all
the musicians look
nearly identical. But
are they?
2
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23.1 Introduction to
Functional Groups
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Functional Groups
Functional Groups
How are organic compounds
classified?
3
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23.1 Introduction to
Functional Groups
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Functional Groups
In most organic reactions, the
saturated hydrocarbon skeletons of
molecules are chemically inert, or nonreactive.
• So how, then, can there be hundreds of
different kinds of organic reactions?
4
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23.1 Introduction to
Functional Groups
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Functional Groups
Most organic chemistry involves
substituents, which are groups attached
to hydrocarbon chains or rings.
• The substituents of organic molecules
often contain oxygen, nitrogen, sulfur,
and/or phosphorus.
5
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23.1 Introduction to
Functional Groups
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Functional Groups
Most organic chemistry involves
substituents, which are groups attached
to hydrocarbon chains or rings.
• The substituents of organic molecules
often contain oxygen, nitrogen, sulfur,
and/or phosphorus.
• They are called functional groups because
they are the chemically functional parts of
the molecules.
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23.1 Introduction to
Functional Groups
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Functional Groups
A functional group is a specific
arrangement of atoms in an organic
compound that is capable of characteristic
chemical reactions.
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23.1 Introduction to
Functional Groups
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Functional Groups
A functional group is a specific
arrangement of atoms in an organic
compound that is capable of characteristic
chemical reactions.
• Note that the double and triple bonds of
alkenes and alkynes are chemically reactive.
• Therefore, they are also considered
functional groups.
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23.1 Introduction to
Functional Groups
>
Functional Groups
Organic compounds can be classified
according to their functional groups.
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23.1 Introduction to
Functional Groups
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Interpret Data
Organic Compounds Classified by Functional Group
Compound
type
Halocarbon
Alcohol
Ether
Amine
Aldehyde
Ketone
General
structure
Functional
group
Halogen
Compound
type
Carboxylic
acid
General
structure
Functional
group
Carbonyl
Hydroxy
Ether
Ester
Ester
Amide
Amide
Amino
Carbonyl
Carbonyl
• In each general structure listed, the symbol R represents any
carbon chains or rings attached to the functional group.
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23.1 Introduction to
Functional Groups
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Interpret Data
Organic Compounds Classified by Functional Group
Compound
type
Halocarbon
Alcohol
Ether
Amine
Aldehyde
Ketone
General
structure
Functional
group
Halogen
Compound
type
General
structure
Carboxylic
acid
Functional
group
Carbonyl
Hydroxy
Ether
Ester
Ester
Amide
Amide
Amino
Carbonyl
Carbonyl
• In some cases, R can be a hydrogen atom.
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23.1 Introduction to
Functional Groups
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Interpret Data
Organic Compounds Classified by Functional Group
Compound
type
Halocarbon
Alcohol
Ether
Amine
Aldehyde
Ketone
General
structure
Functional
group
Halogen
Compound
type
Carboxylic
acid
General
structure
Functional
group
Carbonyl
Hydroxy
Ether
Ester
Ester
Amide
Amide
Amino
Carbonyl
Carbonyl
• When more than one R group is shown in the structural
formula, the groups do not need to be the same.
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23.1 Introduction to
Functional Groups
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Are functional groups always
substituents on a hydrocarbon?
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23.1 Introduction to
Functional Groups
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Are functional groups always
substituents on a hydrocarbon?
No. Alkenes and alkynes are also chemically
reactive. Therefore double and triple bonds can
be considered functional groups, but they are
not substituents.
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23.1 Introduction to
Functional Groups
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Halocarbons
Halocarbons
What is the general formula of a
halocarbon?
15
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23.1 Introduction to
Functional Groups
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Halocarbons
Halocarbons
What is the general formula of a
halocarbon?
• A halocarbon is an organic compound
that contains at least one covalently
bonded fluorine, chlorine, bromine, or
iodine atom.
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Halocarbons
The general formula of a halo
carbon is RX, where X is a halogen
substituent.
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23.1 Introduction to
Functional Groups
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Halocarbons
The IUPAC rules for naming
halocarbons are based on the name of
the parent hydrocarbon.
• The halogen groups are named as
substituents.
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23.1 Introduction to
Functional Groups
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Halocarbons
The IUPAC rules for naming
halocarbons are based on the name of
the parent hydrocarbon.
• The halogen groups are named as
substituents.
Chloromethane
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23.1 Introduction to
Functional Groups
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Halocarbons
The IUPAC rules for naming
halocarbons are based on the name of
the parent hydrocarbon.
• The halogen groups are named as
substituents.
Chloroethene
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23.1 Introduction to
Functional Groups
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Halocarbons
The IUPAC rules for naming
halocarbons are based on the name of
the parent hydrocarbon.
• The halogen groups are named as
substituents.
Chlorobenzene
21
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23.1 Introduction to
Functional Groups
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Halocarbons
Common names of halocarbons consist of two
parts.
• The first part names the hydrocarbon portion of
the molecule as an alkyl group, such as methyl- or
ethyl-.
• The second part names the halogen with an -ide
ending.
Methyl chloride
22
Vinyl chloride
Phenyl chloride
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23.1 Introduction to
Functional Groups
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Halocarbons
• On the basis of their common names, a
halocarbon in which a halogen is
attached to a carbon of an aliphatic
chain is called an alkyl halide.
• A halocarbon in which a halogen is
attached to a carbon of an arene ring is
called an aryl halide.
23
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23.1 Introduction to
Functional Groups
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Interpret Data
Some Common Substituent Groups
Name
24
Group structure
Name
Isopropyl
Tertiary butyl
(tert-butyl)
Isobutyl
Vinyl
Secondary butyl
(sec-butyl)
Phenyl
Group structure
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23.1 Introduction to
Functional Groups
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Halocarbons
The attractions between halocarbon
molecules are primarily the result of
weak van der Waals interactions.
• Generally, these attractions increase with
the degree of halogen substitution.
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23.1 Introduction to
Functional Groups
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Interpret Data
More highly halogenated organic compounds have
higher boiling points.
Comparing Methane and Chloromethanes
Molecular formula
Molar mass (g) Boiling point (°C)
Methane
16.0
–161
CH3Cl
Chloromethane
(methyl chloride)
50.5
–24
CH2Cl2
Dichloromethane
(methylene chloride)
85.0
40
CHCl3
Trichloromethane
(chloroform)
119.5
61
Tetrachloromethane
(carbon tetrachloride)
154.0
74
CH4
CCl4
26
Name
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23.1 Introduction to
Functional Groups
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Halocarbons
Very few halocarbons are found in
nature, but they can be readily prepared
and used for many purposes.
• For example, hydrofluorocarbons (HFCs)
are used as refrigerants in automobile airconditioning systems.
• Halocarbons are also used as solvents
and as ingredients of stretchable
polymers.
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23.1 Introduction to
Functional Groups
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What is the difference between an alkyl
halide and an aryl halide?
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23.1 Introduction to
Functional Groups
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What is the difference between an alkyl
halide and an aryl halide?
An alkyl halide is a halocarbon in which a
halogen is attached to a carbon of an aliphatic
chain. An aryl halide is a halocarbon in which a
halogen is attached to a carbon of an arene
ring.
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23.1 Introduction to
Functional Groups
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Substitution Reactions
Substitution Reactions
How are substitution reactions used
in organic chemistry?
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23.1 Introduction to
Functional Groups
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Substitution Reactions
Organic reactions often proceed more slowly
than inorganic reactions because organic
reactions commonly involve the breaking of
relatively strong covalent bonds.
• They often require catalysts.
• Many organic reactions are complex, and
they usually produce a mixture of products.
– The desired product must then be separated
by distillation, crystallization, or other means.
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Functional Groups
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Substitution Reactions
A common type of organic reaction is a
substitution reaction, in which an
atom, or a group of atoms, replaces
another atom or group of atoms.
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Functional Groups
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Substitution Reactions
Substitution reactions are an
important method of introducing new
functional groups to organic
molecules.
33
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23.1 Introduction to
Functional Groups
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Substitution Reactions
A halogen atom can replace a hydrogen
atom on an alkane to produce a halocarbon.
• The symbol X stands for a halogen in this
generalized equation.
R—H +
Alkane
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X2
Halogen
→
R—X
Halocarbon
+
HX
Hydrogen halide
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23.1 Introduction to
Functional Groups
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Substitution Reactions
A halogen atom can replace a hydrogen
atom on an alkane to produce a halocarbon.
• The symbol X stands for a halogen in this
generalized equation.
R—H +
Alkane
X2
Halogen
→
R—X
Halocarbon
+
HX
Hydrogen halide
• This type of reaction is also called a
halogenation reaction because the reaction
introduces a halogen atom into the molecule.
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23.1 Introduction to
Functional Groups
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Substitution Reactions
Sunlight or another source of ultraviolet
radiation usually serves as a catalyst.
CH4
Methane
36
+
Cl2
UV
→
light
Chlorine
CH3Cl
+
Chloromethane
HCl
Hydrogen
chloride
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23.1 Introduction to
Functional Groups
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Substitution Reactions
Sunlight or another source of ultraviolet
radiation usually serves as a catalyst.
CH4
Methane
+
Cl2
UV
→
light
Chlorine
CH3Cl
+
Chloromethane
HCl
Hydrogen
chloride
• Even under the most controlled conditions, this
simple substitution reaction produces a mixture
of mono-, di-, tri-, and tetrachloromethanes.
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23.1 Introduction to
Functional Groups
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Substitution Reactions
Halogenation of benzene in the presence
of a catalyst causes the substitution of a
hydrogen atom on the ring.
• Iron compounds are often used as catalysts for
substitution reactions in aromatic compounds.
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Substitution Reactions
Halocarbons can be converted to other types
of compounds by substitution reactions.
• Hydroxide ions can displace halogen atoms on
carbon chains to form an alcohol.
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Substitution Reactions
Chemists usually use aqueous solutions of
sodium hydroxide or potassium hydroxide as
the source of hydroxide ions.
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Substitution Reactions
Halocarbons can also be converted to
other halocarbons, amines, or ethers by
similar substitution reactions.
41
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23.1 Introduction to
Functional Groups
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CHEMISTRY
& YOU
Earlier you learned that adding a halogen
substituent to a hydrocarbon affects
certain physical properties. How can you
distinguish between hydrocarbons and
halocarbons in terms of structures and
properties?
42
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23.1 Introduction to
Functional Groups
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CHEMISTRY
& YOU
Earlier you learned that adding a halogen
substituent to a hydrocarbon affects
certain physical properties. How can you
distinguish between hydrocarbons and
halocarbons in terms of structures and
properties?
A halocarbon will contain at least one covalently
bonded fluorine, chlorine, bromine, or iodine atom.
Halocarbons are more reactive than
hydrocarbons, and have higher boiling points.
43
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23.1 Introduction to
Functional Groups
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Name two kinds of substitution
reactions used in organic chemistry.
44
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23.1 Introduction to
Functional Groups
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Name two kinds of substitution
reactions used in organic chemistry.
There are substitution reactions in which a
halogen reacts with an alkane to produce a
halocarbon, and substitution reactions in which
a hydroxide ion reacts with a halocarbon to form
an alcohol.
45
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23.1 Introduction to
Functional Groups
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Key Concepts
Organic compounds can be classified
according to their functional groups.
The general formula of a halocarbon is
RX, where X is a halogen substituent.
Substitution reactions are an important
method of introducing new functional
groups to organic molecules.
46
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23.1 Introduction to
Functional Groups
>
Glossary Terms
• functional group: a specific arrangement of
atoms in an organic compound that is
capable of characteristic chemical reactions;
the chemistry of an organic compound is
determined by its functional groups
• halocarbon: any member of a class of
organic compounds containing covalently
bonded fluorine, chlorine, bromine, or iodine
47
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23.1 Introduction to
Functional Groups
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Glossary Terms
• alkyl halide: a halocarbon in which one or
more halogen atoms are attached to the
carbon atoms of an aliphatic chain
• aryl halide: a halocarbon in which one or
more halogens are attached to the carbon
atoms of an arene ring
• substitution reaction: a common type of
organic reaction; involves the replacement of
an atom or group of atoms by another atom
or group of atoms
48
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23.1 Introduction to
Functional Groups
>
BIG IDEA
Carbon Chemistry and Reactions
• Functional groups affect the physical and
chemical properties of organic compounds.
• Chemical reactions can be used to change the
structure of organic molecules, often by
introducing a new functional group.
• Substitution reactions are commonly used in
organic chemistry.
49
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23.1 Introduction to
Functional Groups
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END OF 23.1
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