Download 23.2 Alcohols, Ethers, and Amines

23.2 Alcohols, Ethers, and Amines >
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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23.2 Alcohols, Ethers, and Amines >
CHEMISTRY
& YOU
How can organic chemistry cool you
down?
Aftershave lotion
contains a certain
organic compound
that imparts a cooling
sensation on the skin.
2
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23.2 Alcohols, Ethers, and Amines > Alcohols
Alcohols
What is the general formula of an
alcohol?
3
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23.2 Alcohols, Ethers, and Amines > Alcohols
What do mouthwash, perfume, and
hairspray have in common?
• They all contain an alcohol of some type.
• An alcohol is an organic compound with
an —OH group.
4
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23.2 Alcohols, Ethers, and Amines > Alcohols
The general formula of an alcohol is
ROH.
5
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23.2 Alcohols, Ethers, and Amines > Alcohols
The —OH functional group in alcohols is
called a hydroxy group, sometimes
called a hydroxyl group.
• The oxygen atom in the —OH group has
two pairs of electrons, which compress the
R—O—H bond angle.
• As a result, an alcohol molecule has a bent
shape.
6
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23.2 Alcohols, Ethers, and Amines > Alcohols
Aliphatic alcohols can be classified into
structural categories according to the
number of carbons attached to the carbon
with the hydroxy group.
• If only one carbon (or no carbon) is attached
to C—OH, the latter carbon is considered a
primary carbon, and the alcohol is a primary
alcohol.
Only one R group is attached to C—OH
of a primary (abbreviated 1°) alcohol.
7
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23.2 Alcohols, Ethers, and Amines > Alcohols
Aliphatic alcohols can be classified into
structural categories according to the
number of carbons attached to the carbon
with the hydroxy group.
• If two carbons are attached, the carbon is a
secondary carbon, which gives a secondary
alcohol.
Two R groups are attached to C—OH of
a secondary (2°) alcohol.
8
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23.2 Alcohols, Ethers, and Amines > Alcohols
Aliphatic alcohols can be classified into
structural categories according to the
number of carbons attached to the carbon
with the hydroxy group.
• If three carbons are attached, the carbon is
a tertiary carbon, and a tertiary alcohol.
Three R groups are attached to C—OH of
a tertiary (3°) alcohol.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
Both IUPAC and common names are used
for alcohols.
10
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
To name aliphatic alcohols using the IUPAC
system, drop the -e ending of the parent
hydrocarbon name and add the ending -ol.
• The parent hydrocarbon is the longest
continuous chain of carbons that includes the
carbon attached to the hydroxy group.
Ethanol
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
To name aliphatic alcohols using the IUPAC
system, drop the -e ending of the parent
hydrocarbon name and add the ending -ol.
• The parent hydrocarbon is numbered so the
position of the hydroxy group is given the
lowest possible number.
2-propanol
12
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
Some alcohols have more than one hydroxy
group.
• To name these alcohols using the IUPAC
system, simply add the ending -diol or -triol to
the parent hydrocarbon name if the alcohol has
two or three hydroxy groups, respectively.
1,2-ethanediol
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1,2,3-propanetriol
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
The common names of aliphatic alcohols
are written in the same way as those of
halocarbons.
• The alkyl group ethyl, for example, is named
and followed by the word alcohol, as in ethyl
alcohol.
Ethyl alcohol
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
The common names of aliphatic alcohols
are written in the same way as those of
halocarbons.
• The alkyl group ethyl, for example, is named
and followed by the word alcohol, as in ethyl
alcohol.
Ethyl alcohol
• The common name for an alcohol with two
hydroxy groups is glycol.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
When the hydroxy group is attached directly
to an aromatic ring, the compound is called
a phenol.
• To assign the IUPAC name, phenol is used as
the parent hydrocarbon.
2-methylphenol
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23.2 Alcohols, Ethers, and Amines > Alcohols
Naming Alcohols
When the hydroxy group is attached directly
to an aromatic ring, the compound is called
a phenol.
• To assign the IUPAC name, phenol is used as
the parent hydrocarbon.
– Cresol is the common name for the o, m, and p
constitutional isomers of methylphenol.
2-methylphenol
(o-cresol)
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23.2 Alcohols, Ethers, and Amines >
18
Interpret Data
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23.2 Alcohols, Ethers, and Amines > Alcohols
Properties of Alcohols
Alcohols are capable of intermolecular
hydrogen bonding, which is reflected in
their physical properties.
• Alcohols boil at higher temperatures than
alkanes and halocarbons containing a
comparable number of atoms.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Properties of Alcohols
Because alcohols are derivatives of water,
they are somewhat soluble in water.
• Alcohols with up to four carbons are completely
soluble in water.
• The solubility of alcohols with more than four
carbons in the chain is usually much lower.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Properties of Alcohols
Alcohols consist of two parts—the carbon
chain and the hydroxy group.
• The carbon chain part is nonpolar and is not
attracted to water.
• The hydroxy group is polar and strongly
interacts with water through hydrogen bonding.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Properties of Alcohols
Alcohols consist of two parts—the carbon
chain and the hydroxy group.
• For alcohols of up to four carbons, the polarity
of the hydroxy group overpowers the
nonpolarity of the carbon chain.
– As a result, these alcohols are soluble in water.
22
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23.2 Alcohols, Ethers, and Amines > Alcohols
Properties of Alcohols
Alcohols consist of two parts—the carbon
chain and the hydroxy group.
• For alcohols of up to four carbons, the polarity
of the hydroxy group overpowers the
nonpolarity of the carbon chain.
– As a result, these alcohols are soluble in water.
• As the number of carbon atoms increases, the
nonpolarity of the carbon chain dominates, and
the solubility of the alcohol decreases.
23
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23.2 Alcohols, Ethers, and Amines > Alcohols
Uses of Alcohols
2-propanol, which is more
familiarly known as rubbing
alcohol, is often used as an
antiseptic.
24
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23.2 Alcohols, Ethers, and Amines > Alcohols
Uses of Alcohols
1,2,3-propanetriol is highly
soluble in water because it
has three hydroxy groups.
• It has a tendency to absorb
water from its surroundings.
• This quality makes it a
valuable moistening agent in
cosmetics, foods, and
pharmaceuticals.
25
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23.2 Alcohols, Ethers, and Amines > Alcohols
Uses of Alcohols
Some antifreezes use 1,2-ethanediol as the
main ingredient.
• This alcohol has a high boiling point, 197°C,
which helps prevent vehicle engines from
overheating.
• Its advantages over liquids with high boiling
points are its solubility in water and its low
freezing point, –17.4°C.
26
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23.2 Alcohols, Ethers, and Amines > Alcohols
Uses of Alcohols
Most ethanol is produced by yeast
fermentation of sugar.
• Fermentation is the production of ethanol from
sugars by the action of yeasts or bacteria.
– The enzymes of the yeasts or bacteria serve
as catalysts for the transformation.
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23.2 Alcohols, Ethers, and Amines > Alcohols
Uses of Alcohols
Bread rises because of fermentation.
• Glucose molecules in the dough are broken
down by the following fermentation reaction.
C6H12O6(aq) → 2CH3CH2OH(aq) + 2CO2(g)
Glucose
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Ethanol
Carbon dioxide
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23.2 Alcohols, Ethers, and Amines >
What functional group do all alcohols
contain?
29
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23.2 Alcohols, Ethers, and Amines >
What functional group do all alcohols
contain?
All alcohols contain an —OH functional
group.
30
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Addition Reactions
How are addition reactions used in
organic chemistry?
31
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
The carbon-carbon single bonds in
alkanes are not easy to break. In an
alkene, however, one of the bonds in the
double bond is somewhat weaker.
• This bond is easier to break than a carboncarbon single bond.
• So, it is sometimes possible for a
compound of general structure X—Y to add
to a double bond.
32
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
The carbon-carbon single bonds in
alkanes are not easy to break. In an
alkene, however, one of the bonds in the
double bond is somewhat weaker.
• In an addition reaction, a substance is
added at the double or triple bond of an
alkene or alkyne.
33
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Addition reactions are an important
method of introducing new functional
groups to organic molecules. They are
also used to convert alkenes to alkanes.
34
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
In the general addition reaction shown
below, X and Y represent the two parts
of the compound that are added to the
alkene.
35
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Hydration Reactions
The addition of water to an alkene is a
hydration reaction.
• A hydration reaction results in the formation of
an alcohol.
• The addition of water to ethane to form ethanol
is a typical hydration reaction.
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Halogenation Reactions
When the reagent X—Y is a halogen
molecule, the product of the reaction is a
disubstituted halocarbon.
• The addition of bromine to ethene to form the
disubstituted halocarbon 1,2-dibromoethane
is an example.
37
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Halogenation Reactions
The addition of bromine to carbon-carbon
multiple bonds is often used as a chemical
test for unsaturation in an organic molecule.
• Bromine has an orange color, but most
bromine-substituted organic compounds are
colorless.
After mixing, if the
solution remains
colorless, the
compound is
positive for
unsaturation.
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If the solution
remains orange,
the compound is
negative for
unsaturation.
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Halogenation Reactions
Hydrogen halides, such as HBr or HCl,
can also add to a double bond.
• Because the product contains only one
substituent, it is called a monosubstituted
halocarbon.
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Hydrogenation Reactions
The addition of hydrogen to a carboncarbon double bond to produce an alkane
is called a hydrogenation reaction.
• The manufacture of margarine or spreads from
various oils is a common application of
hydrogenation.
– Saturated fats have higher
melting points than unsaturated
fats. This is why margarine
remains solid at room
temperature.
40
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23.2 Alcohols, Ethers, and Amines > Addition Reactions
Hydrogenation Reactions
The hydrogenation of a double bond is a
reduction reaction.
• Ethene is
reduced to
ethane.
• Cyclohexene is
reduced to
cyclohexane.
41
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23.2 Alcohols, Ethers, and Amines >
How are hydration and hydrogenation
reactions similar? How are they
different?
42
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23.2 Alcohols, Ethers, and Amines >
How are hydration and hydrogenation
reactions similar? How are they
different?
Both hydration and hydrogenation reactions are
addition reactions. Hydration is the addition of
water to an alkene, and results in the formation of
an alcohol. Hydrogenation is the addition of
hydrogen, and results in the formation of an
alkane.
43
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23.2 Alcohols, Ethers, and Amines > Ethers
Ethers
What is the general formula of an
ether?
44
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23.2 Alcohols, Ethers, and Amines > Ethers
Ethers
What is the general formula of an
ether?
• An ether is an organic compound in
which oxygen is bonded to two carbon
groups.
45
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23.2 Alcohols, Ethers, and Amines > Ethers
The general formula of an ether is ROR.
• Like an alcohol, an ether molecule is bent
because of the unshared pairs of electrons
on the oxygen atom.
46
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23.2 Alcohols, Ethers, and Amines > Ethers
To name an ether using the IUPAC system,
first you need to identify the two R groups.
• The smaller R group is treated as part of the
substituent, and the -ane and -ene endings are
replaced with -oxy.
• The larger R group is the parent hydrocarbon.
47
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23.2 Alcohols, Ethers, and Amines > Ethers
In the common names of ethers, both R
groups are treated as substituents.
• The -ane or -ene endings are replaced with -yl
for both R groups.
• List the names of the two R groups in
alphabetical order and follow with the word
ether.
48
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23.2 Alcohols, Ethers, and Amines >
CHEMISTRY
& YOU
Menthol is the common name of the
organic compound responsible for the
cooling sensation in many consumer
products. Menthol is a cyclohexanol with
two alkyl substituents. Is menthol an
alcohol or an ether? How can you tell?
49
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23.2 Alcohols, Ethers, and Amines >
CHEMISTRY
& YOU
Menthol is the common name of the
organic compound responsible for the
cooling sensation in many consumer
products. Menthol is a cyclohexanol with
two alkyl substituents. Is menthol an
alcohol or an ether? How can you tell?
Menthol is an alcohol. The ending -ol
always indicates an alcohol. An
ether is indicated by the ending -oxy
or by the word “ether.”
50
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23.2 Alcohols, Ethers, and Amines > Ethers
When both R groups are the same, the
ether is symmetric.
• The common names of symmetric ethers use
the prefix di-.
51
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23.2 Alcohols, Ethers, and Amines > Ethers
Diethyl ether was the first reliable general
anesthetic.
• However, because
diethyl ether is highly
flammable and often
causes nausea, it was
eventually replaced by
other anesthetics.
52
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23.2 Alcohols, Ethers, and Amines > Ethers
• Ethers usually have lower boiling points than
alcohols of comparable molar mass, but higher
boiling points than comparable hydrocarbons
and halocarbons.
• Unlike alcohols, ethers are not capable of
forming hydrogen bonds with other ether
molecules.
• Ethers can form hydrogen bonds with water.
– Ethers are more soluble in water than hydrocarbons
and halocarbons, but less soluble than alcohols
because they form fewer hydrogen bonds.
53
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23.2 Alcohols, Ethers, and Amines >
What is the key difference between a
symmetric ether and an asymmetric
ether?
54
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23.2 Alcohols, Ethers, and Amines >
What is the key difference between a
symmetric ether and an asymmetric
ether?
A symmetric ether has two of the same R
groups attached to the oxygen atom; an
asymmetric ether has two different R
groups.
55
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23.2 Alcohols, Ethers, and Amines > Amines
Amines
What is the general formula of an
amine?
56
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23.2 Alcohols, Ethers, and Amines > Amines
Amines
What is the general formula of an
amine?
• An amine is an organic compound in
which nitrogen is bonded to a carbon
group.
– Amines are similar to ammonia (NH3).
57
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23.2 Alcohols, Ethers, and Amines > Amines
The general formula of an amine is
RNH2, R2NH, or R3N.
58
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23.2 Alcohols, Ethers, and Amines > Amine
Amines can be classified according to the
number of R groups attached to the nitrogen
atom.
• An amine with the general formula RNH2 is a
primary amine because one R group is
attached to the nitrogen atom.
• Amines with two or three R groups attached
to the nitrogen atom are secondary or tertiary
amines, respectively.
59
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23.2 Alcohols, Ethers, and Amines > Amines
The IUPAC system for naming primary amines
is similar to that of alcohols.
• The -e ending of the parent hydrocarbon is
changed to -amine.
– Ethanamine is used to make plastics,
pharmaceuticals, and pesticides.
– Benzenamine is used to make furniture foam and
some of the dyes that give clothes their colors.
Ethanamine
60
Benzenamine
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23.2 Alcohols, Ethers, and Amines > Amines
The common names of primary amines
are similar to the IUPAC names.
• The alkyl or aryl group is named and
followed by -amine.
61
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23.2 Alcohols, Ethers, and Amines > Amines
Like alcohols, primary amines form
intermolecular hydrogen bonds.
• Because nitrogen is less electronegative than
oxygen, the hydrogen bonds in amines are not as
strong as those in alcohols.
– As a result, primary amines have lower boiling points
than alcohols with a comparable number of carbons.
• Amines can also hydrogen bond with water.
– Smaller amines are soluble in water, but as the
number of carbons increase, the solubility in water
decreases.
62
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23.2 Alcohols, Ethers, and Amines >
What functional group is characteristic
of primary amines?
63
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23.2 Alcohols, Ethers, and Amines >
What functional group is characteristic
of primary amines?
Primary amines are characterized by
having an —NH2 group.
64
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23.2 Alcohols, Ethers, and Amines > Key Concepts
The general formula of an alcohol is ROH.
Addition reactions are an important method
of introducing new functional groups to
organic molecules. They are also used to
convert alkenes to alkanes.
The general formula of an ether is ROR.
The general formula of an amine is RNH2,
R2NH, or R3N.
65
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23.2 Alcohols, Ethers, and Amines > Glossary Terms
• alcohol: an organic compound having an —OH
(hydroxy) group; the general structure is
R—OH
• hydroxy group: the —OH functional group in
alcohols
• fermentation: the production of ethanol from
sugars by the action of yeast or bacteria
• addition reaction: a reaction in which a
substance is added at the double bond of an
alkene or at the triple bond of an alkyne
66
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23.2 Alcohols, Ethers, and Amines > Glossary Terms
• hydration reaction: a reaction in which water
is added to an alkene
• hydrogenation reaction: a reaction in which
hydrogen is added to a carbon-carbon double
bond to produce an alkane
• ether: an organic compound in which oxygen is
bonded to two carbon groups; the general
formula is R—O—R
• amine: an organic compound in which nitrogen
is bonded to a carbon group
67
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23.2 Alcohols, Ethers, and Amines >
BIG IDEA
Carbon Chemistry and Reactions
• Chemical reactions can be used to
change the structure of organic
molecules, often by introducing a new
functional group.
• Addition reactions are commonly used
in organic chemistry.
68
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23.2 Alcohols, Ethers, and Amines >
END OF 23.2
69
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