Chapter 8 Aromaticity Reactions of Benzene and Substituted Benzenes 1.
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Transcript of Chapter 8 Aromaticity Reactions of Benzene and Substituted Benzenes 1.
Chapter 8
Aromaticity
Reactions of Benzene and
Substituted Benzenes
1
The first structure for benzene was
proposed by August Kekulé in 1872.
2
3
We often represent benzene as a hybrid of two equivalent structures
4
To name a benzene ring with one substituent, name the substituent and add the word benzene.
Naming Benzene Compounds
5
Common Names
OMe CH3 OH NH2
anisole toluene phenol aniline
CHO COOH CNstyrene benzaldehyde benzoic acid benzonitrile
6
ortho-dibromobenzene
or
o-dibromobenzene
or 1,2-dibromobenzene
meta-dibromobenzene
or
m-dibromobenzene
or 1,3-dibromobenzene
para-dibromobenzene
or
p-dibromobenzene
or 1,4-dibromobenzene
7
• If the two groups on the benzene ring are different, alphabetize the names of the substituents preceding the word benzene.
• If one substituent is part of a common root, name the molecule as a derivative of that monosubstituted benzene.
8
For three or more substituents on a benzene ring:
1. Number to give the lowest possible numbers around the ring.
2. Alphabetize the substituent names.
3. When substituents are part of common roots, name the molecule as a derivative of that monosubstituted benzene. The substituent that comprises the common root is located at C1.
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10
Name the following benzene compounds.
11
More practice…..Page 226 Problem 26
Page 214 Problem 14
12
More naming…..
13
Interesting Aromatic Compounds
14
15
Reactions of Benzene: Oxidation
16
What are the products of oxidation of the following compounds?
Another problem…..Page 213 Problem 12
17
Side Chain Bromination
Reaction of an alkylbenzene with N-bromo-succinimide (NBS) and benzoyl peroxide (radical initiator) introduces Br into the side chain.
18
19
Reduction of Aromatic Compounds
Reactions of Benzene: Electrophilic Substitution Vs Electrophilic Addition
20
Electrophilic Aromatic Substitution
21
22
Halogenation
23
Nitration and Sulfonation
24
Friedel-Crafts Alkylation
25
Limitations of Friedel Crafts Reactions
26
Page 212 Problem 11
27
Friedel-Crafts Acylation
28
Di- and Polysubstitution
Existing groups on a benzene ring influence further substitution in both orientation and rate
Orientation certain substituents direct new substitution preferentially
toward ortho-para positions, others direct preferentially toward meta positions
Rate certain substituents are activating toward further
substitution, others are deactivating toward further substitution
29
-OCH3 is ortho-para directing
Ortho-para Directors
30
Meta Directors
31
Types of Substituents
32
Page 218 Problem 18
33
Page 221 Problem 19
34
Trisubstituted Benzenes
35
36
37
Where would the electrophile attack the ring preferentially?
38
Predict the major product of each of the following reactions.
39
Synthesis of p-Bromobenzoic acid
40
The order of steps is important.
41