1. Phenols and Aryl Halides Nucleophilic Aromatic Substitution
Chapter 21
Phenols and Aryl Halides
Nucleophilic Aromatic Substitution

2. About The Authors
These PowerPoint Lecture Slides were created and prepared by Professor William Tam and his wife, Dr. Phillis Chang.
Professor William Tam received his B.Sc. at the University of Hong Kong in 1990 and his Ph.D. at the University of Toronto (Canada) in He was an NSERC postdoctoral fellow at the Imperial College (UK) and at Harvard University (USA). He joined the Department of Chemistry at the University of Guelph (Ontario, Canada) in 1998 and is currently a Full Professor and Associate Chair in the department. Professor Tam has received several awards in research and teaching, and according to Essential Science Indicators, he is currently ranked as the Top 1% most cited Chemists worldwide. He has published four books and over 80 scientific papers in top international journals such as J. Am. Chem. Soc., Angew. Chem., Org. Lett., and J. Org. Chem.
Dr. Phillis Chang received her B.Sc. at New York University (USA) in 1994, her M.Sc. and Ph.D. in 1997 and 2001 at the University of Guelph (Canada). She lives in Guelph with her husband, William, and their son, Matthew.

3. Structure and Nomenclature of Phenols

4. 1A. Nomenclature of Phenols

5. The benzenediols also have common names

6. Naturally Occurring Phenols

7. Physical Properties of Phenols

8. Synthesis of Phenols
4A. Laboratory Synthesis

9. 4B. Industrial Syntheses
Hydrolysis of chlorobenzene (Dow Process)

10. From cumene hydroperoxide

11. Mechanism
Chain initiation

12. Chain propagation

13. Chain propagation

14. Reactions of Phenols as Acids

15. (NO resonance stabilization)

17. 5B. Distinguishing and Separating Phenols from Alcohols and Carboxylic Acids
Question
If you are given three unknown samples: one is benzoic acid; one is phenol; and one is cyclohexyl alcohol; how would you distinguish them by simple chemical tests?
Recall: acidity of

20. Other Reactions of the O–H Group of Phenols

21. 6A. Phenols in the Williamson Synthesis

22. Cleavage of Alkyl Aryl Ethers

23. Reactions of the Benzene Ring of Phenols
Bromination
(NO Lewis acid required for the brominations)

24. Nitration

25. Sulfonation

26. Kolbe reaction

27. Mechanism

29. The Claisen Rearrangement

30. Via a [3,3] sigmatropic rearrangement

31. Quinones

34. Aryl Halides and Nucleophilic Aromatic SubstitutionX

36. 11A. Nucleophilic Aromatic Substitution by Addition–Elimination: The SNAr Mechanism
Nucleophilic aromatic substitution can occur when strong electron-withdrawing groups are ortho or para to the halogen atom

38. The mechanism that operates in these reactions is an addition–elimination mechanism involving the formation of a carbanion with delocalized electrons, called a Meisenheimer intermediate. The process is called nucleophilic aromatic substitution (SNAr)

39. The SNAr mechanism

41. 11B. Nucleophilic Aromatic Substitution through an Elimination–Addition Mechanism: Benzyne

42. The benzyne elimination–addition mechanism

45. X

46. Benzyne intermediates have been “trapped” through the use of Diels–Alder reactions

47. 11C. Phenylation

48. Spectroscopic Analysis of Phenols and Aryl Halides
Infrared spectra (IR)

49. 1H NMR spectra
d 0.5 – 1.0 ppm
intramolecular
hydrogen bonding

50. d 7 – 9 ppm

51. 13C NMR spectra
d 135 – 170 ppm

52. Mass spectra
Mass spectra of phenols often display a prominent molecular ion peak, M+•
Phenols that have a benzylic hydrogen produce an M+• – 1 peak that can be larger than the M+• peak

53.  END OF CHAPTER 21 