Download Alcohols, Phenols, Thiols and Ethers

Alcohols and Phenols
Lecture 4 Alcohols, Phenols, and Thiols
An alcohol contains
ƒ A hydroxyl group
(—OH) attached to
a carbon chain.
A phenol contains
ƒ A hydroxyl group
(—OH) attached to
a benzene ring.
Alcohols, Phenols, and Thiols
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
1
Classification of Alcohols
Learning Check
Alcohols are classified
ƒ By the number of alkyl groups attached to the carbon
bonded to the hydroxyl.
ƒ 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
2
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
3
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Naming Alcohols
More Names of Alcohols
The names of alcohols
ƒ In the IUPAC system replace -e of alkane name with ol.
ƒ 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
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
methyl alcohol
6
5
4
3
2
5-methyl-2-hexanol
1
ethyl alcohol
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Some Typical Alcohols
“rubbing alcohol”
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Learning Check
OH
|
CH3—CH—CH3
Give the IUPAC name for each of the following:
1. CH3—CH2—CH2—CH2—OH
2-propanol (isopropyl alcohol)
antifreeze
HO—CH2—CH2—OH
2.
1,2-ethanediol (ethylene glycol)
glycerol
OH
|
HO—CH2—CH—CH2—OH
1,2,3-propanetriol
OH CH3
|
|
CH3—CH—CH—CH2—CH3
OH
3.
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Publishing as Benjamin Cummings
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Learning Check
Naming Phenols
To name a phenol with two substituents,
ƒ Assign C-1 to the carbon attached to the –OH.
ƒ Number the ring to give the lowest numbers.
ƒ Use prefixes o, m, and p for common names.
Write the structure of the following:
A. 3-pentanol
B.
ethyl alcohol
C.
3-methylcyclohexanol
OH
OH
OH
Cl
Br
Phenol
9
3-chlorophenol
(m-chlorophenol)
4-bromophenol
(p-bromophenol)
10
Phenols in Medicine
Derivatives of Phenol
Phenol
ƒ Is the IUPAC name for benzene with a hydroxyl
group.
ƒ Is used in antiseptics and disinfectants.
ƒ Compounds of phenol are the active ingredients in the
essential oils of cloves, vanilla, nutmeg, and mint.
OH
OH
OH
OH
OH
CH2CH2CH2CH2CH2CH3
phenol
resorcinol
4-hexylresorcinol
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3
Learning Check
Thiols
Write the structure of each of the following:
Thiols
ƒ Are carbon compounds
that contain a –SH
group.
A.
3-pentanol
B.
ethyl alcohol
C.
p-methylphenol
ƒ Are named in the IUPAC
system by adding -thiol
to the alkane name of
the longest carbon chain.
13
Naming Thiols
Thiols
ƒ In thiols with long carbon chains, the chain is numbered
to locate the –SH group.
CH3—CH2—CH2—SH
SH
|
CH3—CH—CH3
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1-propanethiol
2-propanethiol
Thiols
ƒ Often have
strong odors.
ƒ Are used to
detect gas leaks.
ƒ Are found in
onions, oysters,
and garlic.
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Learning Check
Learning Check
Draw the structure of each compound.
A. 2-butanethiol
Name each of the following compounds:
OH
|
A. CH3—CH2 —CH—CH3
B. 2-methyl-1-butanol
CH3
|
B. CH3—CH2—CH—CH2—CH2—OH
C. CH3—CH2—CH2—SH
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Pause: Group Activity
Ethers
Do the following problems on ALE 4
ƒ Problem # 1, parts A to F
ƒ Problem # 2, parts A to D
Ethers
ƒ Contain an ─O─ between two carbon groups.
ƒ 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
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ethyl methyl ether
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5
Ethers as Anesthetics
IUPAC Names for Ethers
ƒ 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
ƒ Numbering the longer alkane gives
1-methoxypropane
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MTBE
Anesthetics
ƒ Inhibit pain signals to the brain.
ƒ Such as ethyl ether CH3─CH2─O─CH2─CH3 were used
for over a century, but caused nausea and were
flammable.
ƒ 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
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Learning Check
Methyl tert-butyl ether
CH3
│
CH3─O─C─CH3
│
CH3
Draw the structure of each compound.
A. diethyl ether
B. ethyl methyl ether
ƒ Is one of the most produced organic chemicals.
C. 2-methoxybutane
ƒ Is a fuel additive
ƒ Is used to improve gasoline combustion.
ƒ Use is questioned since the discovery that MTBE has
contaminated water supplies.
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Cyclic Ethers
Dioxins
A cyclic ether
ƒ Contains an O atom in a carbon ring.
ƒ Is called a heterocyclic compound.
ƒ Typically has 5 (furan) or 6 atoms (pyran) in the
ring.
Dioxins are
ƒ A group of ethers that are highly toxic.
ƒ Formed during forest fires and as industrial byproducts.
ƒ Often carcinogenic.
O
O
furan
O
tetrahydrofuran
O
pyran
O
Cl
O
Cl
Cl
O
1,4-dioxane
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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”)
Learning Check
Pause: Group Activity
Name each of the following:
Do the following problems on ALE 4
ƒ Problem # 1, parts G to I
ƒ Problem # 2, parts E to F
O
1.
2.
CH3
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O
O
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Lecture 4
Boiling Points of Alcohols
Alcohols
ƒ Contain a strongly
electronegative O in the OH
groups.
ƒ Form hydrogen bonds between
alcohol molecules.
ƒ Have higher boiling points than
alkanes and ethers of similar
mass.
13.3
Physical Properties of Alcohols,
Phenols, and Ethers
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
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Solubility of Alcohols and Ethers
in Water
Boiling Points of Ethers
Ethers
ƒ Have an O atom, but
no H is attached.
ƒ Cannot form hydrogen
bonds between ether
molecules.
ƒ Alcohols and ethers are more soluble in water than
alkanes because the oxygen atom hydrogen bonds
with water.
ƒ Alcohols with 1-4 C atoms are soluble, but alcohols
with 5 or more C atoms are not.
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Publishing as Benjamin Cummings
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Comparing Solubility and Boiling
Points
Compound
Alkane
CH3─CH2─CH3
Molar Boiling
Mass Point (°C)
44
-42
Soluble
in Water?
No
Ether
CH3─O─CH3
46
-23
Yes
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Yes
Solubility of Phenol
Phenol
ƒ Is soluble in water.
ƒ Has a hydroxyl group that ionizes slightly (weak
acid).
ƒ Is corrosive and irritating to the skin.
OH
Alcohol CH3─CH2─OH
O-
+ H2O
+ H3O+
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Learning Check
Learning Check
Which compound would have the higher boiling
point? Explain.
Which compound would be more soluble in water?
Explain.
ethyl methyl ether or 1-propanol
ethanol or 2-pentanol
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Pause: Group Activity
Lecture 4
Do the following problems on ALE 4
ƒ Problem # 3
ƒ Problem # 4
13.4
Reactions of Alcohols and Thiols
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Combustion of Alcohols
Dehydration of Alcohols
Combustion is the reaction of an alcohol
with O2 to produce CO2 and H2O.
2CO2 + 4H2O + Heat
2CH3OH + 3O2
Dehydration of an alcohol occurs
ƒ When heated with an acid catalyst.
ƒ 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
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Learning Check
Formation of Ethers
Write the equations for the reactions when
2-propanol undergoes:
1. combustion
ƒ Ethers form when dehydration takes place at low
temperature.
H+
CH3—OH + HO—CH3
CH3—O—CH3 + H2O
two methanol
dimethyl ether
2. dehydration
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Oxidation and Reduction
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Oxidation and Reduction
In the oxidation of an organic compound
ƒ There is an increase in the number of C—O
bonds.
ƒ There is a loss of H.
In the reduction of an organic compound
ƒ There is an decrease in the number of C—O
bonds.
ƒ There is a gain of H.
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Oxidation of Primary (1°)
Alcohols
Oxidation of Secondary (2°)
Alcohols
When a primary alcohol is oxidized [O],
ƒ One H is removed from the –OH.
ƒ Another H is removed from the carbon bonded to the OH.
ƒ An aldehyde is produced.
[O]
Primary alcohol
Aldehyde
OH
O
|
[O]
||
CH3—C—H
CH3—C—H + H2O
|
H
Ethanol
(ethyl alcohol)
Ethanal
(acetaldehyde)
When a secondary alcohol is oxidized [O],
ƒ One H is removed from the –OH.
ƒ Another H is removed from the carbon bonded to the OH.
ƒ A ketone is produced.
[O]
secondary alcohol
ketone
OH
O
│
[O]
║
CH3—C—CH3
CH3—C—CH3 + H2O
│
H
2-propanol (isopropyl alcohol)
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Oxidation of Tertiary (3)°Alcohols
Tertiary alcohols do not readily oxidize.
[O]
Tertiary alcohol
no reaction
OH
│
[O]
no product
CH3─C─CH3
│
no H on the C-OH to oxidize
CH3
2-propanone(dimethyl ketone,
“acetone”) 46
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-methyl-2-propanol
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2) CO2 + H2O
O
||
3) CH3—CH2—C—H
[O]
C. O2, heat
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Oxidation of Ethanol in the Body
Ethanol CH3─CH2─OH
In the body,
ƒ Ethanol is oxidized by enzymes in the liver.
ƒ Aldehyde product impairs coordination.
O
O
║
║
CH3─CH2─OH
CH3─C─H
CH3─C─OH
ethyl alcohol
acetaldehyde
acetic acid
Ethanol
ƒ Acts as a depressant.
ƒ Kills or disables more
people than any other drug.
ƒ Is metabolized at a rate of
12-15 mg/dL per hour by a
social drinker.
ƒ Is metabolized at a rate of 30
mg/dL per hour by an
alcoholic.
2CO2 + H2O
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49
Effect of Alcohol on the Body
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Learning Check
Select the product for the oxidation of
OH
│
[O]
CH3—CH—CH2—CH3
TABLE 13.2
1) CH3—CH=CH—CH3
3) CO2 + H2O
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O
║
2) CH3—C—CH2 —CH3
OH
│
4) CH3—CH—CH2—CH3
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Oxidation of Thiols
Pause: Group Activity
When thiols undergo oxidation,
ƒ An H atom is lost from each of two –SH groups.
ƒ The product is a disulfide.
[O]
CH3—SH + HS—CH3
CH3—S—S—CH3 + H2O
Do the following problems on ALE 4
ƒ Problem # 5
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