Title: Ch. 9 Alcohols, Epoxides,
1Ch. 9 Alcohols, Epoxides, Ethers
diethyl ether
ethylene glycol
glucose
DGEBA
brevetoxin B
2Structure of Alcohols
Alcohols contain an OH group bonded to an sp3
hybridized C
sp3 hybridized C
3Naming Alcohols
1. The parent chain must contain the OH group.
Change parent ending to -ol. 2. Give the OH
the lowest possible number.
6,6-dimethyl-3-heptanol
4Naming Alcohols
3. When the OH group is attached to a ring, it
is assumed to be at carbon 1.
2-methylcyclopentanol (NOT
2-methyl-1-cyclopentanol)
5What is the systematic name for this alcohol?
A) 2,3-diethyl-5,5-dimethyl-2-hexanol B)
4,5-diethyl-2,2-dimethyl-5-hexanol C)
4-ethyl-3,6,6-trimethyl-3-heptanol D)
4-ethyl-2,2,5-trimethyl-5-heptanol E)
1,2-diethyl-1,4,4,-trimethyl-1-pentanol
6What is the systematic name for this alcohol?
A) 7-ethyl-3,3-dimethylcycloheptanol B)
2-ethyl-6,6-dimethyl-1-cycloheptanol C)
4-ethyl-1,1-dimethylcycloheptanol D)
2-ethyl-6,6-dimethylcycloheptanol E)
7-ethyl-3-dimethylcycloheptanol
7Properties of Alcohols
sp3 hybridized
d-
d
d
109o
8Properties of Alcohols
9Which has the highest boiling point?
A B
C
D E
10Properties of Alcohols
Alcohols can act as acids or bases
pKa 16 (weak acid)
11Properties of Alcohols
Alcohols are weak bases
12Preparation of Alcohols
Primary alcohols can be prepared by SN2 reactions
Example-
13Reactions of Alcohols
1. Dehydration loss of H2O to produce an alkene
Order of reactivity 3o gt 2o gt 1o
14Rank the alcohols in order of increasing reactivit
y toward H catalyzed dehydration.
1 2 3
A) 1, 2, 3 B) 3, 2, 1 C) 2, 1, 3 D) 1, 3, 2 E) 2,
3, 1
15Dehydration Reactions of Alcohols
A. Acid-catalyzed dehydration treatment with
strong acids (H2SO4, p-toluenesulfonic acid,
etc) results in dehydration
Example
major minor
16Here is how it happens
17The major product of this reaction is
A B C
D E
18The major product of this reaction is
A B
C
D E
19Dehydration Reactions of Alcohols
Carbocation rearrangements can result in
unexpected products
Rearrangements occur by 1,2-hydride shifts
and 1,2-alkyl shifts
20Here is what happens.
21What is the major product?
A B
C
D E
22Dehydration Reactions of Alcohols
B. Dehydration with POCl3/Pyridine reaction
proceeds by E2 mechanism
Zaitsev product is favored
23What is the major product?
A B
C
D E
24Conversion of Alcohols to Alkyl Halides
2. Alcohols to alkyl halides A. Treatment of
alcohols with HX
X Cl, Br, I
Alcohol Reactivity 3o gt 2o gt 1o HX Reactivity
HI gt HBr gt HCl
25Conversion of Alcohols to Alkyl Halides
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27Conversion of Alcohols to Alkyl Halides
B. Treatment of alcohols with SOCl2 and PBr3
-OH is converted to a good leaving group then
displaced by an SN2 mechanism Used for 1o and
2o alcohols
28Conversion of Alcohols to Alkyl Halides
29Which is the major product?
A B
C
D E
30Which stereoisomer is formed? A) 1 only B) 2
only C) 1 and 2
31Conversion of Alcohols to Tosylates
3. Alcohols to tosylates
Example-
32Reactions of Alkyl Halides/Tosylates
Conversion of OH to a better leaving group
allows substitution and elimination reactions
(Ch. 7 and 8)
33Structure Properties of Ethers
Ethers contain two carbon groups bonded to an
oxygen
The C-O bonds are polar, but ethers cant
hydrogen bond
Ethers are commonly used as solvents because
they are unreactive, low-boiling, and dissolve
many organic compounds
34Naming Ethers
Common names are generally used for simple
ethers List alkyl groups alphabetically
35What is the common name for this ether? A)
1-ethoxybutane B) ethyl butyl ether C) butyl
ethyl ether D) 1-butoxyethane E) ethyl propyl
ether
36Naming Ethers
Systematic naming is used for more complex
ethers Name smaller alkyl group and O as
alkoxy group
4-ethoxy-2-methylheptane
1-ethyl-2-methoxycyclohexane
37What is the systematic name? A)
6-butoxy-3-methylheptane B) 2-butyl-5-methylhepan
e ether C) 2-butoxy-5-methylheptane D)
1-butoxy-1,4-dimethylhexane E)
2-butoxy-5-ethylhexane
38Preparation of Ethers
Williamson ether synthesis most common way to
prepare ethers, SN2 reaction
Example-
Is there another way? Is it better or worse?
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40Reactions of Ethers
Cleavage with HX HBr and HI cleave ethers to
form an alcohol and alkyl halide
For methyl and 1o groups, C-O cleavage occurs by
SN2 For 2o or 3o groups, C-O cleavage occurs by
SN1
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42Structure Properties of Epoxides
Epoxides-cyclic ethers in which the O atom is
part of a three-membered ring
C-O-C bond angle is 60o
43Preparation of Epoxides
1. Intramolecular Williamson ether synthesis
starting material is a halohydrin
Example-
44Preparation of Epoxides
2. Epoxides from Alkenes
most common method for epoxide synthesis more
detail in Ch.10
45Reactions of Epoxides
Epoxides readily undergo ring-opening
reactions The mechanism varies with reaction
conditions 1. Opening with Strong Nucleophiles
Ring opening is SN2 Attack occurs at less
hindered position
46Reactions of Epoxides
47Reactions of Epoxides
2. Opening Under Acidic Conditions
HCl, HBr, and HI react in this way H2O and ROH
require added H Backside attack occurs at more
hindered position
48Reactions of Epoxides
Mechanism has SN2 and SN1 characteristics
49Epoxides and Cancer
benzoapyrene
diol epoxide
Oxidation increases water solubility
50Epoxides and Cancer
dG
Epoxide ring-opening modifies DNA