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Chapter 8

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  1. Chapter 8 Aromaticity Reactions of Benzene and Substituted Benzenes

  2. The first structure for benzene was proposed by August Kekulé in 1872.

  3. We often represent benzene as a hybrid of two equivalent structures

  4. Naming Benzene Compounds To name a benzene ring with one substituent, name the substituent and add the word benzene.

  5. phenol aniline toluene anisole styrene benzaldehyde benzoic acid benzonitrile Common Names

  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: • Number to give the lowest possible numbers around the ring. • Alphabetize the substituent names. • 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. Name the following benzene compounds.

  10. Page 214 Problem 14 More practice….. Page 226 Problem 26

  11. More naming…..

  12. Interesting Aromatic Compounds

  13. Reactions of Benzene: Oxidation

  14. What are the products of oxidation of the following compounds? Another problem…..Page 213 Problem 12

  15. Side Chain Bromination Reaction of an alkylbenzene with N-bromo-succinimide (NBS) and benzoyl peroxide (radical initiator) introduces Br into the side chain.

  16. Reduction of Aromatic Compounds

  17. Reactions of Benzene: Electrophilic Substitution Vs Electrophilic Addition

  18. Electrophilic Aromatic Substitution

  19. Halogenation

  20. Nitration and Sulfonation

  21. Friedel-Crafts Alkylation

  22. Limitations of Friedel Crafts Reactions

  23. Page 212 Problem 11

  24. Friedel-Crafts Acylation

  25. 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-parapositions, others direct preferentially towardmetapositions • Rate • certain substituents are activating toward further substitution, others are deactivatingtoward further substitution

  26. Ortho-para Directors -OCH3 is ortho-para directing

  27. Meta Directors

  28. Types of Substituents

  29. Page 218 Problem 18

  30. Page 221 Problem 19

  31. Trisubstituted Benzenes

  32. Where would the electrophile attack the ring preferentially?

  33. Predict the major product of each of the following reactions.

  34. Synthesis of p-Bromobenzoic acid

  35. The order of steps is important.