Download Alcohols, Phenols, Thiols, & Ethers

Chapter 13 Alcohols, Phenols, and
Thiols
13.1
Alcohols, Phenols, and Thiols
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
1
Alcohols and Phenols
An alcohol contains
 A hydroxyl group
(—OH) attached to
a carbon chain.
A phenol contains
 A hydroxyl group
(—OH) attached to
a benzene ring.
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
2
Classification of Alcohols
Alcohols are classified
 By the number of alkyl groups attached to the carbon
bonded to the hydroxyl.
 As primary (1°), secondary (2°), or tertiary (3°).
Primary (1º)
1 group
H
|
CH3—C—OH
|
H
Secondary (2º)
Tertiary (3º)
2 groups
3 groups
CH3
CH3
|
|
CH3—C—OH
CH3—C—OH
|
|
H
CH3
3
Learning Check
Classify each alcohol as
(P) primary, (S) secondary, or (T) tertiary.
OH
|
1. CH3—CH—CH2—CH3
2. CH3—CH2—CH2—OH
OH
|
3. CH3—CH2—C—CH2—CH3
|
CH3
4
Solution
OH
|
1. CH3—CH—CH2—CH3
(S) secondary
2. CH3—CH2—CH2—OH
(P) primary
OH
|
3. CH3—CH2—C—CH2—CH3
|
CH3
(T) tertiary
5
Naming Alcohols
The names of alcohols
 In the IUPAC system replace -e of alkane name with ol.
 that are common names use the name of the alkyl
group followed by alcohol.
Formula
IUPAC
Common Name
CH4
methane
CH3─OH
methanol
CH3─CH3
ethane
CH3─CH2─OH
ethanol
methyl alcohol
ethyl alcohol
6
More Names of Alcohols
In IUPAC names for longer carbon chains, the chain is
numbered from the end nearest the ─OH group.
CH3─CH2─CH2─OH
1-propanol
OH
│
CH3─CH─CH2─CH3
2-butanol
CH3
OH
│
│
CH3─CH─CH2─CH2─CH─CH3
5-methyl-2-hexanol
6
5
4
3
2
1
7
Some Typical Alcohols
“rubbing alcohol”
OH
|
CH3—CH—CH3
2-propanol (isopropyl alcohol)
antifreeze
HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol)
glycerol
OH
|
HO—CH2—CH—CH2—OH
1,2,3-propanetriol
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Publishing as Benjamin Cummings
8
Learning Check
Give the IUPAC name for each of the following:
1. CH3—CH2—CH2—CH2—OH
2.
OH CH3
|
|
CH3—CH—CH—CH2—CH3
OH
3.
9
Solution
1. CH3—CH2—CH2—CH2—OH
OH CH3
|
|
2. CH3—CH—CH—CH2—CH3
3.
OH
1-butanol
3-methyl-2-pentanol
cyclopentanol
10
Learning Check
Write the structure of the following:
A. 3-pentanol
B.
ethyl alcohol
C.
3-methylcyclohexanol
11
Solution
Write the structure of the following:
A. 3-pentanol
OH
|
CH3—CH2—CH—CH2—CH3
CH3 —CH2 —OH
B.
ethyl alcohol
C.
3-methylcyclohexanol
OH
CH3
12
Naming Phenols
To name a phenol with two substituents,
 Assign C-1 to the carbon attached to the –OH.
 Number the ring to give the lowest numbers.
 Use prefixes o, m, and p for common names.
OH
OH
OH
Cl
Br
Phenol
3-chlorophenol
(m-chlorophenol)
4-bromophenol
(p-bromophenol)
13
Phenols in Medicine
Phenol
 Is the IUPAC name for benzene with a hydroxyl
group.
 Is used in antiseptics and disinfectants.
OH
OH
OH
OH
OH
CH2CH2CH2CH2CH2CH3
phenol
resorcinol
4-hexylresorcinol
14
Derivatives of Phenol
 Compounds of phenol are the active ingredients in the
essential oils of cloves, vanilla, nutmeg, and mint.
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15
Learning Check
Write the structure of each of the following:
A.
3-pentanol
B.
ethyl alcohol
C.
p-methylphenol
16
Solution
Write the structure of each of the following:
A. 3-pentanol
OH
|
CH3—CH2—CH—CH2—CH3
B. ethyl alcohol
CH3—CH2—OH
OH
C. p-methylphenol
CH3
17
Thiols
Thiols
 Are carbon compounds
that contain a –SH
group.
 Are named in the IUPAC
system by adding thiol to
the alkane name of the
longest carbon chain.
18
Naming Thiols
 In thiols with long carbon chains, the chain is numbered
to locate the –SH group.
CH3—CH2—CH2—SH
1-propanethiol
SH
|
CH3—CH—CH3
2-propanethiol
19
Thiols
Thiols
 Often have
strong odors.
 Are used to
detect gas leaks.
 Are found in
onions, oysters,
and garlic.
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20
Learning Check
Draw the structure of each compound.
A. 2-butanethiol
B. 2-methyl-1-butanol
21
Solution
Draw the structure of each compound.
A. 2-butanethiol
SH
|
CH3—CH—CH2—CH3
B. 2-methyl-1-butanol
CH3
|
HO—CH2—CH—CH2—CH3
22
Learning Check
Name each of the following compounds:
OH
|
A. CH3—CH2 —CH—CH3
CH3
|
B. CH3—CH2—CH—CH2—CH2—OH
C. CH3—CH2—CH2—SH
23
Solution
Name each of the following compounds:
OH
|
A. CH3—CH2 —CH—CH3
2-butanol
CH3
|
B. CH3—CH2—CH—CH2—CH2—OH
3-methyl-1-pentanol
C. CH3—CH2—CH2—SH
1-propanethiol
24
Chapter 13 Alcohols, Phenols,
Ethers, and Thiols
13.2
Ethers
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25
Ethers
Ethers
 Contain an ─O─ between two carbon groups.
 That are simple are named by listing the alkyl names
in alphabetical order followed by ether
CH3─O─CH3
CH3─CH2─O─CH3
dimethyl ether
ethyl methyl ether
26
IUPAC Names for Ethers
 In the IUPAC system, the shorter alkyl group and the
oxygen are named as an alkoxy group attached to the
longer alkane.
methoxy
propane
CH3—O—CH2—CH2—CH3
1
2
3
 Numbering the longer alkane gives
1-methoxypropane
27
Ethers as Anesthetics
Anesthetics
 Inhibit pain signals to the brain.
 Such as ethyl ether CH3─CH2─O─CH2─CH3 were used
for over a century, but caused nausea and were
flammable.
 Developed by 1960s were nonflammable.
Cl F
F
Cl F
H
│ │
│
│ │
│
H─C─C─O─C─H
H─C─C─O─C─H
│ │
│
│ │
│
F F
F
H F
H
Ethane(enflurane)
Penthrane
28
MTBE
Methyl tert-butyl ether
CH3
│
CH3─O─C─CH3
│
CH3
 Is one of the most produced organic chemicals.
 Is a fuel additive
 Is used to improve gasoline combustion.
 Use is questioned since the discovery that MTBE has
contaminated water supplies.
29
Learning Check
Draw the structure of each compound.
A. diethyl ether
B. ethyl methyl ether
C. 2-methoxybutane
30
Solution
Draw the structure of each compound.
A. diethyl ether
CH3—CH2—O—CH2—CH3
B. ethyl methyl ether CH3—CH2—O—CH3
C. 2-methoxybutane
O—CH3
|
CH3—CH—CH2—CH3
31
Cyclic Ethers
A cyclic ether
 Contains an O atom in a carbon ring.
 Is called a heterocyclic compound.
 Typically has 5 (furan) or 6 atoms (pyran) in the
ring.
O
O
furan
O
tetrahydrofuran
O
pyran
O
1,4-dioxane
32
Dioxins
Dioxins are
 A group of ethers that are highly toxic.
 Formed during forest fires and as industrial byproducts.
 Often carcinogenic.
O
Cl
O
Cl
Cl
CH2
C OH
2,4,5-trichlorophenoxyacetic acid
(2,4,5-T; agent orange)
Cl
O
Cl
Cl
O
Cl
2,3,7,8-tetrachlorodibenzodioxin
(TTCC, “dioxin”)
33
Learning Check
Name each of the following:
O
1.
2.
CH3
O
O
34
Solution
1.
2.
O
O
CH3
methoxy cyclopentane
(cyclopentyl methyl ether)
1,4-dioxane
O
35
Chapter 13 Alcohols, Phenols,
Ethers, and Thiols
13.3
Physical Properties of Alcohols,
Phenols, and Ethers
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36
Boiling Points of Alcohols
Alcohols
 Contain a strongly
electronegative O in the OH
groups.
 Form hydrogen bonds between
alcohol molecules.
 Have higher boiling points than
alkanes and ethers of similar
mass.
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37
Boiling Points of Ethers
Ethers
 Have an O atom, but
no H is attached.
 Cannot form hydrogen
bonds between ether
molecules.
 Have boiling points
similar to alkanes of
similar mass.
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38
Solubility of Alcohols and Ethers
in Water
 Alcohols and ethers are more soluble in water than
alkanes because the oxygen atom hydrogen bonds
with water.
 Alcohols with 1-4 C atoms are soluble, but alcohols
with 5 or more C atoms are not.
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39
Comparing Solubility and Boiling
Points
Compound
Alkane
CH3─CH2─CH3
Molar Boiling
Mass Point (°C)
44
-42
Ether
CH3─O─CH3
46
-23
Yes
46
78
Yes
Alcohol CH3─CH2─OH
Soluble
in Water?
No
40
Solubility of Phenol
Phenol
 Is soluble in water.
 Has a hydroxyl group that ionizes slightly (weak
acid).
 Is corrosive and irritating to the skin.
OH
O-
+ H2O
+ H3O+
41
Learning Check
Which compound would have the higher boiling
point? Explain.
ethyl methyl ether or 1-propanol
42
Solution
1-propanol would have the higher boiling point because
an alcohol can form hydrogen bonds, but the ether
cannot.
43
Learning Check
Which compound would be more soluble in water?
Explain.
ethanol or 2-pentanol
44
Solution
Ethanol. An alcohol with two carbons in its carbon chain
is more soluble than one with 5 carbons. The longer
alkyl chain diminishes the effect of the –OH group.
45
Chapter 13 Alcohols, Phenols,
Ethers, and Thiols
13.4
Reactions of Alcohols and Thiols
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46
Combustion of Alcohols
Combustion is the reaction of an alcohol
with O2 to produce CO2 and H2O.
2CH3OH + 3O2
2CO2 + 4H2O + Heat
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47
Dehydration of Alcohols
Dehydration of an alcohol occurs
 When heated with an acid catalyst.
 With the loss of —H and —OH from adjacent carbon
atoms.
H OH
|
|
H+, heat
H—C—C—H
H—C=C—H + H2O
|
|
| |
H H
H H
alcohol
alkene
48
Learning Check
Write the equations for the reactions when
2-propanol undergoes:
1. combustion
2. dehydration
49
Solution
OH
│
CH3─CH─CH3 = 2-propanol = C3H8O
1. combustion
2C3H8O + 9O2
2. dehydration
OH
│
CH3─CH─CH3
6CO2 + 8H2O
H+
CH3─CH=CH2 + H2O
50
Formation of Ethers
 Ethers form when dehydration takes place at low
temperature.
H+
CH3—OH + HO—CH3
CH3—O—CH3 + H2O
two methanol
dimethyl ether
51
Oxidation and Reduction
In the oxidation of an organic compound
 There is an increase in the number of C—O
bonds.
 There is a loss of H.
In the reduction of an organic compound
 There is an decrease in the number of C—O
bonds.
 There is a gain of H.
52
Oxidation and Reduction
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53
Oxidation of Primary (1)
Alcohols
When a primary alcohol is oxidized [O],
 One H is removed from the –OH.
 Another H is removed from the carbon bonded to the OH.
 An aldehyde is produced.
[O]
Primary alcohol
Aldehyde
OH
O
|
[O]
||
CH3—C—H
CH3—C—H + H2O
|
H
Ethanol
(ethyl alcohol)
Ethanal
(acetaldehyde)
54
Oxidation of Secondary (2)
Alcohols
When a secondary alcohol is oxidized [O],
 One H is removed from the –OH.
 Another H is removed from the carbon bonded to the OH.
 A ketone is produced.
[O]
secondary alcohol
ketone
OH
O
│
[O]
║
CH3—C—CH3
CH3—C—CH3 + H2O
│
H
2-propanol (isopropyl alcohol)
2-propanone(dimethyl ketone,
“acetone”) 55
Oxidation of Tertiary (3)Alcohols
Tertiary alcohols do not readily oxidize.
[O]
Tertiary alcohol
no reaction
OH
│
[O]
CH3─C─CH3
no product
│
CH3
no H on the C-OH to oxidize
2-methyl-2-propanol
56
Learning Check
Select the compound that would result for each reaction
of CH3—CH2—CH2—OH.
1) CH3—CH=CH2
A. H+, heat
B.
2) CO2 + H2O
O
||
3) CH3—CH2—C—H
[O]
C. O2, heat
57
Solution
CH3—CH2—CH2—OH
A. H+, heat
B.
[O]
C. O2, heat
1) CH3—CH=CH2
O
||
3) CH3—CH2—C—H
2) CO2 + H2O
58
Oxidation of Ethanol in the Body
In the body,
 Ethanol is oxidized by enzymes in the liver.
 Aldehyde product impairs coordination.
O
O
║
║
CH3─CH2─OH
CH3─C─H
CH3─C─OH
ethyl alcohol
acetaldehyde
acetic acid
2CO2 + H2O
59
Ethanol CH3─CH2─OH
Ethanol
 Acts as a depressant.
 Kills or disables more
people than any other drug.
 Is metabolized at a rate of
12-15 mg/dL per hour by a
social drinker.
 Is metabolized at a rate of 30
mg/dL per hour by an
alcoholic.
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Publishing as Benjamin Cummings
60
Effect of Alcohol on the Body
TABLE 13.2
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61
Learning Check
Select the product for the oxidation of
OH
│
[O]
CH3—CH—CH2—CH3
1) CH3—CH=CH—CH3
3) CO2 + H2O
O
║
2) CH3—C—CH2 —CH3
OH
│
4) CH3—CH—CH2—CH3
62
Solution
Select the product for the oxidation of
OH
│
[O]
CH3—CH—CH2—CH3
O
║
2) CH3—C—CH2—CH3
63
Oxidation of Thiols
When thiols undergo oxidation,
 An H atom is lost from each of two –SH groups.
 The product is a disulfide.
[O]
CH3—SH + HS—CH3
CH3—S—S—CH3 + H2O
64