Chapter 8 Aromaticity Reactions of Benzene and Substituted Benzenes 1
The first structure for benzene was proposed by August Kekulé in
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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 anisole toluene phenolaniline styrenebenzaldehydebenzoic acidbenzonitrile 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. 9
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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
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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
-OCH 3 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
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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