1. 15.REACTIONS OF AROMATIC COMPOUNDS. Electrophilic Aromatic Substitution. ( approx. lecture time: 4 lectures) Topics covered: 15.1-15.14. TNT, useful compound! Ibuprofen (Motrin, Advil), useful compound! Electrophilic Aromatic Substitution

2. Examples of Electrophilic Aromatic Substitution

3. Mechanism of Electrophilic Aromatic Substitution

4. Reaction Coordinate Diagram rate determining step

5. Bromination of Benzene

6. Thyroxine Goiter, enlargement of the thyroid glad due to insufficient dietary iodine (Human hormone that controls metabolism) Made by electrophilic aromatic substitution of Iodine on tyrosine Why do you need iodine in your diet?

7. Nitration of Benzene

8. Friedel-Crafts Alkylation of Benzene

9. ( Not necessary to start with alkyl halide; other possible functional groups can be used to generate a reactive carbocation)

10. Friedel-Crafts Alkylation of Benzene When the carbocation formed can rearrange to a more stable one, it does; the major products obtained from the reaction are those from the more stable carbocation.

11. Friedel-Crafts Acylation of Benzene some acyl groups

12. Mechanism

13. Friedel-Crafts Acylation of Benzene

14. Friedel-Crafts Alkylation and Acylation of Benzene (Additional Points to Remember) Do not use them for Friedel-Crafts reaction Aryl and vinyl halides cannot be used for Fridel- Crafts alkylations

15. Electrophilic Aromatic Substitution of Substituted Benzenes (What happens when the benzene ring already has a substituent?) Only one of two possible outcomes is observed: 1. or 2.

17. The Effect of Activating and Deactivating Substituents

18. What happens when you carry out electrophilic substitution on a benzene with an activating substituent ? result is ortho and para substitution

19. What happens when you carry out electrophilic substitution on a benzene with an deactivating substituent? (** except for F, Cl, Br, I**) result is meta substitution

20. What happens when you carry out electrophilic substitution on a benzene with a halogen (F, Cl, Br, I), which is weakly deactivating ? result is ortho and para substitution

21. Silent Spring (52 nd anniversary) Silent Spring (52 nd anniversary) (How an aromatic organic compound started the environmental movement) “Silent Spring” is Rachel Carson’s book published in 1962 documenting the detrimental effects of pesticides (e.g., DDT) on birds and the environment. The book is considered to have started the environmental movement. DDT was later banned in 1972 in the US. DDT, “DichloroDiphenyl- Trichloroethane”) BPA, “bisphenol A” Both of these compounds made by simple electrophilic aromatic substitution