Chapter Fourteen
Alcohols, Phenols,
And Ethers
Functional Groups
• Groups of atoms within a larger molecule that have
characteristic chemical behavior.
• A functional group behaves almost the _____ way in
every molecule it is in (electronic structure, reactivity,
geometry all generally stay the ______).
• The chemistry of every organic molecule is determined
by the functional groups it contains.
• It is very important for this course that you learn to
recognize functional groups.
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Functional Groups
Name
Alkane
(Not a
functional Group)
Structure
C
Alkene
Alkyne
Arene
(aromatic ring)
H3C
C
C
H2C
C
C
Example
C
CH3
CH2
HC
CH
H
C
C
C
C
C
C
C
HC
CH
HC
CH
C
H
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Functional Groups
Name
Structure
Halide
C
Alcohol
C
X
Example
H3C
OH
H3C
C
H3C
Cl
OH
Ether
C
O
O
CH3
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Alcohols, Phenols, and Ethers cont’d
Fig. 14.1
Space-filling models for the three simplest unbranched chain
alcohols: methyl alcohol, ethyl alcohol, and propyl alcohol.
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The Bonding of Oxygen
• To understand the bonding patterns of oxygen, we
must review what we know about oxygen
– How many valence electrons does oxygen have?
– How many electrons does oxygen need to have an octet
of electrons in its valence shell?
– Oxygen’s octet is filled when it forms ___ bonds to other
atoms:
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Alcohols, Phenols, and Ethers cont’d
→ Fig. 14.2
The similar shapes of
water and methanol.
Methyl alcohol may be
viewed structurally as
an alkyl derivative of
water.
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Classifying Alcohols
• Alcohols are classified by the number of carbon
substituents bonded to the carbon.
– primary (1o)
– secondary (2o)
– tertiary (3o)
R
C
H
Primary
R
H
H
OH
R
C
OH
R
Secondary
R
C
OH
R
Tertiary
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Alcohols, Phenols, and Ethers cont’d
Which are
primary?
Which are
secondary?
Which are
tertiary?
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Alcohols Used As Fuels and Fuel
Additives
← Fig. 14.3
Racing cars are fueled
with methyl alcohol.
Jonathan Ferrey/Getty Images
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Ethyl Alcohol In Beverages and Other
Consumer Products
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Commercial Uses of Alcohols
← Fig. 14.5
Ethylene glycol is the
major ingredient in deicers for planes.
© Hank Morgan/Rainbow
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Metabolic Alcohols
→ Fig. 14.6
For survival in northern
winters, many fish and
insects produce large
amount of glycerol that
dissolve in their blood,
thereby lowering the
freezing point.
James Cotier/Getty Images
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Naming Alcohols
 A carbon compound that contain -OH (hydroxyl)
group
 In IUPAC name, the -e in alkane name is replaced
with -ol.
CH4 methane
CH3OH
CH3CH3
methanol
(methyl alcohol)
ethane
CH3CH2OH ethanol
(ethyl alcohol)
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Naming Alcohols, Part II
 IUPAC names for longer chains number the chain from the
end nearest the -OH group.
CH3CH2CH2OH
1-propanol
OH
CH3CHCH3
CH3
2-propanol
OH
CH3CHCH2CH2CHCH3
5-methyl-2-hexanol
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Some Typical Alcohols
OH
“rubbing alcohol”
CH3CHCH3
2-propanol (isopropyl alcohol)
antifreeze HO-CH2-CH2-OH
1,2-ethanediol (ethylene glycol)
OH
glycerol
HO-CH2-CH-CH2OH
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Name these alcohols.
OH
HO
OH
OH
OH
OH
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Alcohols, Phenols, and Ethers cont’d
Fig. 14.7
(a) The polar hydroxyl functional group dominates the physical
properties of methanol. (b) Conversely, the nonpolar portion of 1octanol dominates its physical properties.
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Alcohols, Phenols, and Ethers cont’d
← Fig. 14.8
(a) Boiling
points and (b)
solubilities in
water of
selected 1alcohols.
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Alcohols, Phenols, and Ethers cont’d
Table 14.3
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Alcohols, Phenols, and Ethers cont’d
← Fig. 14.10
Alcohol boiling points
are higher than those
of the corresponding
alkanes because of the
alcohol-alcohol
hydrogen bonding.
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Alcohols, Phenols, and Ethers cont’d
→ Fig. 14.11
Because of hydrogen
bonding between
alcohol molecules and
water molecules, small
molecular mass
alcohols have unlimited
solubility in water.
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Synthesis of Alcohols
• Alcohols can be prepared from many other kinds of
compounds.
• Hydration!
R-X
Alkyl halides
Ketones
Aldehydes
Esters
R-C-R
=O
–
–
–
–
R=R
=O
– Alkenes
R-OH
alcohol
R-C-H
R-O-R
• They can also be transformed into a wide assortment of
compounds.
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• Preparation by hydration of alkenes.
H2O
H2SO4
H2O
H2SO4
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• Aldehyde and ketone reduction (adding
hydrogen across the double bond) reactions:
O
1. NaBH4, ethanol
2. H3O+
R
O
1. NaBH4, ethanol
R
R
2. H3O+
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Reactions of Alcohols
Combustion
2CH3OH + 3O2
2CO2 + 4H2O + Heat
Dehydration
H OH
H+, heat
H-C-C-H
H H
alcohol
H-C=C-H + H2O
H H
alkene
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Alcohols, Phenols, and Ethers cont’d
← Fig. 14.12
In an intramolecular
alcohol dehydration the
components of water
are removed from
neighboring carbon
atoms. This is an
elimination reaction.
Ch 14 | 27 of 52
Reactions of Alcohols: Dehydration
• Dehydration of an alcohol produces an _________
• Phenols __________ undergo dehydration
• Zaitsev’s rule
– The major product in an intramolecular alcohol dehydration reaction is
the ________ that has the greatest number of alkyl groups attached to
the carbon atoms of the double bond
OH
H2O, 50 oC
H2SO4
H2O, 50 oC
H2SO4
HO
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Reactions of Alcohols:
Intermolecular Alcohol Dehydration
• Ethers form when two alcohols dehydrate at a
____ temperature (140oC)
– H3C-OH + HO-CH3  H3C-O-CH3 + H2O
– Two methanol  dimethyl ether + water
– Note: Dehydration to an alkene at _____oC
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Reactions of Alcohols:
Oxidation and Reduction
• In organic chemistry, an easy way to recognize
oxidation:
– An increase in the number of C-O bonds OR
– A loss of hydrogen atoms
• In organic chemistry, an easy way to recognize
reduction:
– A decrease in the number of C-O bonds OR
– A gain of hydrogen atoms
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• Oxidation of alcohols.
• Valuable reaction to yield carbonyl (C=O) compounds.
– Product depends on starting alcohol and amount of oxidizer.
O
OH
O
Oxidizing agent
R
O
OH
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O
• Oxidation of alcohols.
– Primary alcohols
yield aldehydes
and carboxylic
acids.
– Secondary alcohols
yield ketones.
– Tertiary alcohols
do not react.
From primary
alcohols
O
From primary
alcohols
OH
O
From secondary
alcohols
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• Oxidation reactions:
O
OH
PCC*
CH2Cl2
R
R
O
OH
CrO3, H3O+
or Na2Cr2O7, H2O, CH3CO2H
R
R
OH
O
OH
CrO3, H3O+
R
R
or Na2Cr2O7, H2O, CH3CO2H
R
R
R-OH  R(CO)R or RCHO  RCOOH
* PCC = Pyridinium chlorochromate
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• Levels of oxidation of secondary alcohols:
– Ketone (Most oxidized)
– Alcohol (Least oxidized)
• Levels of oxidation of primary alcohols:
– Carboxylic Acid (Most oxidized)
– Aldehyde
– Alcohol (Least oxidized)
O
OH
Least Oxidized
OH
Most Oxidized
O
O
OH
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Reactions of Alcohols: Halogenation
• Substitution reactions
– Halogen replaces the hydroxyl group
– Reactants: Phosphorus trihalides (with heat)
– 3R-OH + PX3  3R-X + H3PO3
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Chemistry at a Glance:
Summary of Reactions Involving Alcohols
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Phenols
→ Fig. 14.14
Phenol molecule
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• Phenols.
– Phenols are named as seen in Chapter 13.
– Use “phenol” as the parent name instead of
benzene.
OH
H3C
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Phenols in Medicine
Phenols are weak acids and are used as antiseptics
OH
OH
OH
OH
OH
CH2CH2CH2CH2CH2CH3
Phenol
Resorcinol
(antiseptic)
4-Hexylresorcinal
(antiseptic)
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Ethers
→ Fig. 14.17
The similar shapes of
water and dimethyl
ether molecules.
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Ethers
← Fig. 14.18
Alcohols and ethers
with the same number
of carbon atoms and
the same degree of
saturation are structural
isomers.
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CC 14.3 Marijuana
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PHEW !
→ Fig. 14.21
Thiols are responsible
for the strong odor of
"essence of skunk.“
What is the chemical
composition of a thiol,
and how does it relate
to alcohols?
Thiols contain sulfur, in
particular a R–S-H
group.
Jeff Lepore/Photo Researchers
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Ch 14 | 45 of 52
Alcohols, Phenols, and Ethers cont’d
Ch 14 | 46 of 52
Thiols
 Many thiols have disagreeable odors
 Used to detect gas leak
 Found in onions, oysters, garlic and oysters
Onions CH3CH2CH2-SH 1-propanethiol
Garlic CH2= CHCH2-SH 2-propene-1-thiol
Skunk spray
CH3
trans-2-butene-1-thiol
CH = CH
CH2SH
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Alcohols, Phenols, and Ethers cont’d
← Fig. 14.22
A comparison
involving dimethyl
ether and
demethyl sulfide.
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Properties of Ethers
•
•
•
•
•
Non-polar
Low boiling points
Anesthetic (diethylether)
Flammable
React slowly with oxygen to form unstable
hydroperoxides and perioxides
• However, generally unreactive
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Ethers
• Contain an oxygen atom between ______ carbon
atoms
• Simple ethers are named by listing the alkyl
names in alphabetical order followed by “ether”
– CH3-O-CH3
– CH3-O-CH2CH3
– CH3-CH2-O-CH2CH3
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• Ethers (naming).
– Simple ethers that contain no other functional groups: name the
two organic groups and add the word “ether.”
– Otherwise, use “alkoxy” as the substituent name.
O
O
O
O
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Ethers as Anesthetics




Anesthetics inhibit pain signals to the brain
CH3CH2-O-CH2CH3 used for over a century (Morton, 1846)
Causes nausea and is highly flammable
1960s developed nonflammable anesthetics
Cl F F
Cl F H
H-C-C-O-C-H
F F
F
Ethane(enflurane)
H-C-C-O-C-H
H F
H
Penthrane
Ch 14 | 52 of 52