Download Chapter 12 Organic Compounds with Oxygen and Sulfur Alcohols

Chapter 12 Organic Compounds
Alcohols
with Oxygen and Sulfur
An alcohol contains a hydroxyl group (—OH) attached to a
carbon chain.
12.1
Alcohols, Thiols, and Ethers
A phenol contains a hydroxyl group (—OH) attached to a
benzene ring.
Copyright © 2009 by Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
1
Naming Alcohols
More Names of Alcohols
IUPAC names for longer chains number the chain from
the end nearest the -OH group.
The names of alcohols
• in the IUPAC system replace the -e with -ol.
• with common names use the name of the alkyl group
followed by alcohol.
Formula
IUPAC
CH4
methane
CH3─OH
methanol
CH3─CH3
ethane
CH3─CH2─OH
ethanol
2
Common Name
CH3─CH2─CH2─OH
1-propanol
OH
│
CH3─CH─CH2─CH3
2-butanol
OH
CH3
│
│
CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-hexanol
6
5
4
3
2
1
methyl alcohol
ethyl alcohol
3
Some Typical Alcohols
Learning Check
OH
|
“Rubbing alcohol” CH3—CH—CH3
2-propanol (isopropyl alcohol)
Antifreeze
Name the following compounds.
1. CH3—CH2—CH2—CH2—OH
HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol)
OH
|
Glycerol
HO—CH2—CH—CH2—OH
1,2,3-propanetriol
4
2.
OH CH3
|
|
CH3—CH—CH—CH2—CH3
OH
3.
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6
Solution
1. CH3—CH2—CH2—CH2—OH
OH CH3
|
|
2. CH3—CH—CH—CH2—CH3
Phenols in Medicine
1-butanol
Phenol
• is the IUPAC name for benzene with a hydroxyl group.
• is used in antiseptics and disinfectants.
3-methyl-2-pentanol
OH
OH
OH
OH
3.
cyclopentanol
OH
OH
CH2CH2CH2CH2CH2CH3
Phenol
Resorcinol
4-hexylresorcinol
7
Derivatives of Phenol
8
Naming Phenols
Compounds of phenol are the active ingredients in the
essential oils of cloves, vanilla, nutmeg, and mint.
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.
OH
1
OH
1
3
Cl
3-chlorophenol
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4
Br
4-bromophenol
9
Learning Check
10
Solution
A.
3-pentanol
Write the structure of each of the following:
A. 3-pentanol
OH
|
CH3—CH2—CH—CH2—CH3
B.
ethyl alcohol
B. ethyl alcohol
C.
4-methylphenol
Write the structure of each of the following:
CH3—CH2—OH
OH
C. 4-methylphenol
CH3
11
12
Classification of Alcohols
Learning Check
Classification of alcohols is
• determined by the number of alkyl groups attached to
the carbon bonded to the hydroxyl.
• primary (1°), secondary (2°), or tertiary (3°).
Primary (1º)
1 group
H
|
CH3—C—OH
|
H
Secondary (2º)
Classify each alcohol as
1) primary, 2) secondary, or 3) tertiary.
OH
|
A. CH3—CH—CH2—CH3
Tertiary (3º)
2 groups
3 groups
CH3
|
CH3—C—OH
|
H
CH3
|
CH3—C—OH
|
CH3
B. CH3—CH2—CH2—OH
OH
|
C. CH3—CH2—C—CH2—CH3
|
CH3
13
14
Thiols
Solution
OH
|
A. CH3—CH—CH2—CH3
secondary
B. CH3—CH2—CH2—OH
primary
OH
|
C. CH3—CH2—C—CH2—CH3
|
CH3
tertiary
Thiols
• contain sulfur
• are similar to alcohols
• contain a thiol (-SH) group
• often have strong odors
• found in cheese, onions, garlic,
and oysters
• are used to detect gas leaks
15
Thiols
16
Ethers
An ether
• contains an ─O─ between two carbon groups.
• has a common name that gives the alkyl names of the attached
groups, followed by ether.
CH3─O─CH3 CH3─CH2─O─CH3
Thiols
• are named in the IUPAC
system by adding thiol to
the alkane name of the
longest carbon chain.
dimethyl ether
ethyl methyl ether
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17
18
Learning Check
Solution
A. 3-pentanol
OH
|
CH3─CH2─CH─CH2─CH3
B. ethanethiol
CH3─CH2─SH
C. diethyl ether
CH3─CH2─O─CH2─CH3
Write the structure of the following.
A. 3-pentanol
B. ethanethiol
C. diethyl ether
19
MTBE
Ethers as Anesthetics
Anesthetics
• inhibit pain signals to the brain.
• like diethyl ether, CH3─CH2─O─CH2─CH3, were used
for over a century, but caused nausea and were
flammable.
• developed by the 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
Ethrane (enflurane)
20
Methyl tert-butyl ether
CH3
│
CH3─O─C─CH3
│
CH3
• is second in production of organic chemicals.
• is an additive used to improve gasoline performance.
• use is questioned since the discovery that MTBE has
contaminated water supplies.
Penthrane
21
Chapter 12 Organic Compounds
with Oxygen and Sulfur
22
Boiling Points of Alcohols
12.2
Properties of Alcohols and Ethers
Alcohols
• contain polar OH
groups.
• form hydrogen bonds
with other alcohol
molecules.
• have higher boiling
points than alkanes and
ethers of similar mass.
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23
24
Solubility of Alcohols and Ethers in
Water
Boiling Points of Ethers
Alcohols and ethers
• are more soluble in water than alkanes because the
oxygen atom can hydrogen bond with water.
• with 1-4 C atoms are soluble, but not with 5 or more
C atoms.
Ethers
• do not have a polar
group.
• have an O atom, but
there is no H attached.
• cannot form hydrogen
bonds between ether
molecules.
Copyright © 2009 by Pearson Education, Inc.
Copyright © 2009 by Pearson Education, Inc.
25
Comparing Boiling Points and
Solubility
26
Solubility of Phenol
Phenol
• is soluble in water.
• has a hydroxyl group that ionizes slightly (weak acid).
• is corrosive and irritating to skin.
OH
O-
+ H2O
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+ H3O+
27
Learning Check
28
Solution
Indicate if each of the following is soluble in water
and explain why:
1. CH3 ─CH2─CH2─CH2─CH2─CH2 ─OH
2. CH3─O─CH2─CH3
3. CH3─CH2─CH2─OH
Indicate if each of the following is soluble in water
and explain why:
1. CH3─CH2─ CH2─CH2─CH2─CH2─OH
No; an alcohol with a long carbon chain (nonpolar)
is not soluble.
2. CH3─O─CH2─CH3 Yes; an O atom can hydrogen
bond with water.
3. CH3─CH2─CH2─OH Yes; short-chain alcohols
hydrogen bond with water.
29
30
Chapter 12 Organic Compounds
with Oxygen and Sulfur
Combustion of Alcohols
12.3
Reactions of Alcohols and Thiols
Alcohols undergo combustion with O2 to produce CO2
and H2O.
CH3—CH2—OH + 3O2
2CO2 + 3H2O + Energy
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31
Dehydration of Alcohols
Learning Check
Alcohols undergo
• dehydration when heated with an acid catalyst.
• 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
32
Write the equations for the reaction of 2-propanol when it
undergoes
1. combustion.
2. dehydration.
alkene
33
Solution
Oxidation and Reduction
OH
│
CH3─CH─CH3 = 2-propanol = C3H8O
1. combustion
2C3H8O + 9O2
2. dehydration
OH
│
CH3─CH─CH3
34
In an oxidation,
• there is an increase in the number of C-O bonds.
• there is a loss of H.
In a reduction,
• there is a decrease in the number of C-O bonds.
• there is a gain of H.
6CO2 + 8H2O
H+
CH3─CH=CH2 + H2O
35
36
Oxidation and Reduction
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
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Ethanol
(ethyl alcohol)
Ethanal
(acetaldehyde)
37
Oxidation of Secondary (2°)
Alcohols
Oxidation of Tertiary (3°) 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
OH
│
CH3─C─CH3
│
ketone
[O]
38
O
║
CH3─C─CH3 + H2O
Tertiary (3°) alcohols do not readily oxidize.
[O]
Tertiary alcohol
no reaction
OH
[O]
│
no product
CH3─C─CH3
│
CH3
no H to oxidize
2-methyl-2-propanol
H
2-propanol (isopropyl alcohol)
2-propanol (dimethyl ketone)
39
Ethanol, CH3CH2OH
Oxidation of Ethanol in the Body
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.
In the body,
• enzymes in the liver oxidize ethanol.
• the aldehyde produced impairs coordination.
• blood alcohol over 0.4% can be fatal.
O
O
║
║
CH3CH2OH
CH3CH
CH3COH
2CO2 + H2O
Ethyl alcohol
Acetaldehyde
40
Acetic acid
41
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42
Alcohol Contents in Common
Products
Effect of Alcohol on the Body
% Ethanol
50%
40%
15-25%
20%
12%
10%
3-9%
Product
Whiskey, rum, brandy
Flavoring extracts
ListerineTM, ScopeTM
Formula 44DTM
Wine, DristanTM
NyquilTM, CepacolTM
Beer, LavorisTM
43
Oxidation of Thiols
44
Learning Check
Select the product for the oxidation of
OH
│
[O]
CH3─CH─CH2─CH3
When thiols undergo oxidation,
• an H atom is lost from each of two –SH groups.
• the product is a disulfide.
[O]
CH3─S─S─CH3 + H2O
CH3─SH + HS─CH3
1) CH3─CH=CH─CH3
3) CO2 + H2O
O
║
2) CH3─C─CH2 ─CH3
OH
│
4) CH3─CH─CH2─CH3
45
Solution
46
Learning Check
Select the product for the oxidation of
OH
│
[O]
CH3─CH─CH2─CH3
Select the product when CH3—CH2—CH2—OH
undergoes each of the following reactions:
H+, heat
[O]
A)
B)
C) + O2
1) CH3—CH=CH2
O
║
2) CH3─C─CH2 ─CH3
2) CO2 + H2O
O
||
—CH
—C—H
3) CH3
2
47
48
Chapter 12 Organic Compounds
with Oxygen and Sulfur
Solution
A. H+, heat
B.
1) CH3—CH=CH2
O
||
3) CH3—CH2—C—H
C. + O2
2) CO2 + H2O
[O]
12.4
Aldehydes and Ketones
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49
Carbonyl Group in Aldehydes and
Ketones
50
Naming Aldehydes
An aldehyde
• has an IUPAC name in which the -e in the alkane name is changed
to –al.
• has a common name for the first four aldehydes that use the
prefixes: form (1C), acet (2C), propion (3C), and butyr (4C),
followed by aldehyde.
O
O
O
║
║
║
CH3─CH2─C─H
H─C─H
CH3─C─H
Ethanal
Propanal
Methanal
A carbonyl group
• in an aldehyde is
attached to at least
one H atom.
• in a ketone is
attached to two
carbon groups.
(formaldehyde)
(acetaldehyde)
(propionaldehyde)
51
Naming Aldehydes
52
Aldehydes in Flavorings
Several naturally occurring aldehydes are used as
flavorings for foods and fragrances.
O
C
H
Benzaldehyde (almonds)
O
CH=CH C
H
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Cinnamaldehyde (cinnamon)
53
54
Ketones in Common Use
Naming Ketones
In naming ketones
• in the IUPAC system, the -e in the alkane name is replaced with –
one.
• with a common name, the alkyl groups attached to the carbonyl
group are named alphabetically, followed by ketone.
O
O
║
║
CH3─C─CH2─CH3
Propanone
CH3 ─C─CH3
(dimethyl ketone)
2-butanone
(ethyl methyl ketone)
Nail polish remover,
solvent
Propanone,
dimethylketone, acetone
Butter flavoring
55
Learning Check
56
Solution
Classify each as 1) aldehyde or 2) ketone.
O
O
||
||
B. CH3—C—H
A. CH3—CH2—C—CH3
A. (2) ketone
B. (1) aldehyde
C. (1) aldehyde
O
CH3
|
||
C. CH3—C—CH2—C—H
|
CH3
D.
D. (2) ketone
O
57
Learning Check
Classify each as an
1) aldehyde, 2) ketone,
O
║
A. CH3─CH2─C─CH3
CH3
O
│
║
C. CH3─C─CH2─C─H
│
CH3
58
Solution
3) alcohol, or
O
║
A. CH3─CH2─C─CH3
2) ketone
4) ether.
B. CH3─O─CH3
4) ether
B. CH3─O─CH3
O
CH3
│
║
C. CH3─C─CH2─C─H
│
CH3
1) aldehyde
OH
│
D. CH3─CH─CH3
59
OH
│
D. CH3─CH─CH3
3) alcohol
60
Learning Check
Solution
Name each of the following:
O
║
1. CH3─CH2─CH2─CH2─C─H
Name each of the following:
O
║
1. CH3─CH2─CH2─CH2─C─H
O
║
2. Cl─CH2─CH2─C─H
O
║
3. CH3─CH2─C─CH3
O
║
2. Cl─CH2─CH2─C─H
O
║
3. CH3─CH2─C─CH3
pentanal
3-chloropropanal
2-butanone;
ethyl methyl ketone
61
Learning Check
Name the following compounds:
O
||
A. CH3—CH2—CH2—C—CH3
62
Solution
B.
O
O
CH3
|
||
C. CH3—C—CH2—C—H
|
CH3
A.
2-pentanone; methyl propyl ketone
B.
cyclohexanone
C.
3,3-dimethylbutanal
63
64
Solution
Learning Check
Draw the structural formulas for each:
O
CH3
│
║
A. 4-methylpentanal
CH3─CH─CH2─CH2─C─H
Draw the structural formulas for each:
A. 4-methylpentanal
B. 2,3-dichloropropanal
C. 3-methyl-2-butanone
65
B. 2,3-dichloropropanal
Cl
O
│
║
Cl─CH2─CH─C─H
C. 3-methyl-2-butanone
CH3 O
│
║
CH3─CH─C─CH3
66
Chapter 12 Organic Compounds
with Oxygen and Sulfur
Physical Properties
12.5
Properties of Aldehydes and Ketones
• The polar carbonyl group provides dipole-dipole
interactions.
δ+ δ-
δ+ δ-
C=O
C=O
• Without an H on the oxygen, aldehydes and
ketones cannot form hydrogen bonds.
Copyright © 2009 by Pearson Education, Inc.
67
Boiling Points
68
Comparison of Boiling Points
Aldehydes and ketones have
• polar carbonyl groups (C=O).
δ+ δ-
C=O
• attractions between polar groups.
δ+ δ-
δ+ δ-
C=O
C=O
• higher boiling points than alkanes and ethers of
similar mass.
Copyright © 2009 by Pearson Education, Inc.
• lower boiling points than alcohols of similar mass.
69
Solubility in Water
70
Learning Check
The electronegative O atom of the carbonyl group of
aldehydes and ketones forms hydrogen bonds with water.
Indicate if each is soluble or insoluble in water.
A. CH3—CH2—CH3
B. CH3—CH2—OH
O
||
C. CH3—CH2—CH2—C—H
O
||
D. CH3—C—CH3
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71
72
Solution
Tollens’ Test
In Tollens’ test,
Indicate if each is soluble or insoluble in water.
A. CH3—CH2—CH3
insoluble
B. CH3—CH2—OH
soluble
O
||
C. CH3—CH2—CH2—C—H
soluble
O
||
D. CH3—C—CH3
soluble
• Tollens’ reagent,
which contains Ag+,
oxidizes aldehydes,
but not ketones.
• Ag+ is reduced to
metallic Ag, which
appears as a
“mirror” in the test
tube.
73
Benedict’s Test
74
Learning Check
In Benedict’s test,
Write the structure and name of the organic
product when each is mixed with Tollens’ reagent.
• Benedict’s reagent,
which contains Cu2+,
reacts with aldehydes
that have an adjacent
OH group.
A. Butanal
B. Acetaldehyde
• an aldehyde is oxidized
to a carboxylic acid,
while Cu2+ is reduced to
give red Cu2O(s).
C. Ethyl methyl ketone
75
76
Chapter 12 Organic Compounds
with Oxygen and Sulfur
Solution
A. Butanal
O
||
CH3—CH2—CH2—C—OH
Butanoic acid
B. Acetaldehyde
O
||
CH3—C—OH
Acetic acid
12.6
Chiral Molecules
C. Ethyl methyl ketone
None.
Ketones are not oxidized by Tollen’s reagent.
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77
78
Some Everyday Chiral and Achiral
Objects
Chiral Objects
Chiral objects
• have the same number of atoms
arranged differently in space.
• have one or more chiral carbon
atoms, each of which is bonded
to four different groups.
• are like your hands. Try to
superimpose your thumbs,
palms, back of hands, and little
fingers.
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79
80
Achiral Structures are
Superimposable
Mirror Images
When the mirror image of an achiral structure is
rotated, the structure can be aligned with the initial
structure. Thus this mirror image is superimposable.
• The mirror images of chiral compounds cannot be
superimposed.
• When the H and I atoms are aligned, the Cl and Br
atoms are on opposite sides.
81
Solution
Learning Check
Identify each as a chiral or an achiral compound.
Cl
Cl
H
C
CH3
CH2CH3
A.
H
82
C
Identify each as a chiral or an achiral compound.
CH3
H
C
H
Br
B.
C.
Cl
Cl
Cl
H
CH3
C
CH3
CH2CH3
83
H
C
Cl
CH3
H
H
C
CH3
Br
A.
B.
C.
chiral
achiral
chiral
84
Fischer Projections
Drawing Fischer Projections
A Fischer projection
• is a 2-dimensional representation of a 3-dimensional
molecule.
• places the most oxidized group at the top.
• uses vertical lines in place of dashes for bonds that
go back.
• uses horizontal lines in place of wedges for bonds
that come forward.
85
D
and L Notations
86
Learning Check
• By convention, the letter L is assigned to the structure
with the —OH on the left.
• The letter D is assigned to the structure with the —OH
on the right.
Indicate whether each pair is a mirror image that
cannot be superimposed (enantiomers).
CH2OH
CH2OH
A.
H
C
CH3
and
Br
H
C
H
87
Solution
Indicate whether each pair is a mirror image that
cannot be superimposed (enantiomers).
CH2OH
CH2OH
A.
H
C
CH3
and
Br
H
C
H
H
Yes
Br
Cl
B.
CH3 C
No
Cl
CH3
and
CH3 C
H
H
89
H
Br
Cl
B.
CH3 C
Cl
CH3
and
CH3 C
H
H
88