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Chapter 17

Chapter 17. Alcohol & Phenol ROH & ArOH. Chapter 17. Naming Properties Synthesis Reactions. 5-methyl-2,4-hexanediol. 2-methyl-4-phenyl-2-butanol. 4,4-Dimethylcyclohexanol. trans -2-Bromocyclopentanol. 4-Bromo-3-methyl-phenol. ( o = ortho(1,2), m = meta(1,3), p = para(1,4)).

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Chapter 17

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  1. Chapter 17 Alcohol & Phenol ROH & ArOH Chapter 17 - Alcohol & Phenol

  2. Chapter 17 • Naming • Properties • Synthesis • Reactions Chapter 17 - Alcohol & Phenol

  3. 5-methyl-2,4-hexanediol Chapter 17 - Alcohol & Phenol

  4. 2-methyl-4-phenyl-2-butanol Chapter 17 - Alcohol & Phenol

  5. 4,4-Dimethylcyclohexanol Chapter 17 - Alcohol & Phenol

  6. trans-2-Bromocyclopentanol Chapter 17 - Alcohol & Phenol

  7. 4-Bromo-3-methyl-phenol Chapter 17 - Alcohol & Phenol

  8. (o = ortho(1,2), m = meta(1,3), p = para(1,4)) 2-(2-Hydroxyethyl)phenol o-(2-Hydroxyethyl)phenol Chapter 17 - Alcohol & Phenol

  9. Chapter 17 • Naming • Properties • Synthesis • Reactions Chapter 17 - Alcohol & Phenol

  10. Properites • Hydrogen bonding • Acidity and Basicity Chapter 17 - Alcohol & Phenol

  11. Hydrogen Bonding H2O HF H2Te NH3 H2Se H2S SnH4 …extrapolation GeH4 SiH4 CH4 1. Water, HF, and NH3 show unusually high bp. 2. Dotted lines depict bp if there were no H-bonding. 3. All others follow normal trend. Chapter 17 - Alcohol & Phenol

  12. Chemical Bond, intramolecular, 150 - 600 kJ/mol Hydrogen bond, intermolecular, 4 - 25 kJ/mol Hydrogen Bonding in Water + + + + -- -- + + -- + + + -- + -- Chapter 17 - Alcohol & Phenol

  13. Hydrogen Bonding in Alcohol + + - - + - + + - - Chapter 17 - Alcohol & Phenol

  14. Hydrogen Bonding and Boiling Point Chapter 17 - Alcohol & Phenol

  15. Properites • Hydrogen bonding • Acidity and Basicity Chapter 17 - Alcohol & Phenol

  16. Acidity & Basicity Like water, alcohol can act as an acid or as a base. base acid oxonium ion alkoxide ion acid base phenoxide ion Chapter 17 - Alcohol & Phenol

  17. 1. Why does the reaction shift to the right? 2. Why is phenoxide ion stable? 3. Why is phenol acidic (compare to water)? ……. Chapter 17 - Alcohol & Phenol

  18. 2. Stable anion implies the following reaction will proceed to the right, Resonance, Stability, Acid Strength 1. Resonance structures implies stability. 3. Stable anion also implies that phenol is a stronger acid than water. Chapter 17 - Alcohol & Phenol

  19. Substituted Phenol Which one is more acidic and why? Chapter 17 - Alcohol & Phenol

  20. To examine the acid strength, Chapter 17 - Alcohol & Phenol

  21. 1. has more resonance structures than ,so it is more stable. . 3. Since 1 is true, that means is more reactive than . 4. Since 3 is true, is more acidic than Resonance, Stability, Acid Strength 2. Fifth structure shows that nitro is an electron-withdrawing group. 5. See page 663 for para position effect. Chapter 17 - Alcohol & Phenol

  22. pKa 9.95 10.17 Resonance, Stability, Acid Strength 1. Phenol is more acidic than p-methylphenol. 2. pKa indicates that CH3– is an electron-donating group. Chapter 17 - Alcohol & Phenol

  23. Arrange the order of acidity (from highest to lowest) of the following compounds and explain why. Chapter 17 - Alcohol & Phenol

  24. Answer Key 4-methoxylphenol (least acidic) phenol 4-nitrobenzylphenol (most acidic) Reason: The nitro- on4-nitrobenzylphenol is an electron-withdrawing group which enhances the aciditiy compare to phenol. The methoxy- of 4-methoxylphenol is an electron-donating group, thus it is less acidic than phenol. Chapter 17 - Alcohol & Phenol

  25. Chapter 17 • Naming • Properties • Synthesis • Reactions Chapter 17 - Alcohol & Phenol

  26. Synthesis • Hydroboration, Oxymercuration, Hydroxylation. • Reaction with peroxide. • Reduction of carbonyl compounds. Chapter 17 - Alcohol & Phenol

  27. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 17 - Alcohol & Phenol

  28. Synthesis • Hydroboration, Oxymercuration, Hydroxylation. • Reaction with peroxide. • Reduction of carbonyl compounds. Chapter 17 - Alcohol & Phenol

  29. Also from alkene 1-Methyl-1,2-epoxy- cyclohexane 1-Methyl- trans-1,2-cyclohexanol Chapter 17 - Alcohol & Phenol

  30. Synthesis • Hydroboration, Oxymercuration, Hydroxylation. • Reaction with peroxide. • Reduction of carbonyl compounds. Chapter 17 - Alcohol & Phenol

  31. Reduction of Aldehyde & Ketone Reducing Agents: 1. NaBH4, ethanol, H+ 2. LiAlH4, ether, H+ Chapter 17 - Alcohol & Phenol

  32. Reduction of Carboxylic Acid & Ester Reducing Agents: LiAlH4, ether, H+ Chapter 17 - Alcohol & Phenol

  33. Carbonyl compounds + Grignard reagent Chapter 17 - Alcohol & Phenol

  34. Chapter 17 • Naming • Properties • Synthesis • Reactions Chapter 17 - Alcohol & Phenol

  35. Reactions • Dehydration  alkenes • With HX  alkyl halides • With Tosylates • Oxidation - 1o, 2o, & 3o • Protection of alcohol Chapter 17 - Alcohol & Phenol

  36. Synthesis of Alkene From halides - dehydrohalogenation (minus HX): Elimination From alcohol - dehydration (minus H2O): Chapter 7 slide 5 Chapter 17 - Alcohol & Phenol

  37. Dehydration 1. Watch for Zaitsev’s rule!!! 2. Only 3o alcohols are readily dehydrated with acid. 3. 2o alcohols are dehydrated under mild basic condition. 4. Alcohol dehydration via E2. Chapter 17 - Alcohol & Phenol

  38. Dehydration Mechanism E1 Chapter 17 - Alcohol & Phenol

  39. Reactions • Dehydration  alkenes • With HX  alkyl halides • With Tosylates • Oxidation - 1o, 2o, & 3o • Protection of alcohol Chapter 17 - Alcohol & Phenol

  40. Alcohol to Alkyl Halide SN2 Chapter 17 - Alcohol & Phenol

  41. Reactions • Dehydration  alkenes • With HX  alkyl halides • With Tosylates • Oxidation - 1o, 2o, & 3o • Protection of alcohol Chapter 17 - Alcohol & Phenol

  42. p-toluenesulfonyl Chloride (p-TosCl) ROTos Chapter 17 - Alcohol & Phenol

  43. With Tosylate C–O broken Inversion Inversion R S R C–O not broken No inversion Inversion S R R Chapter 17 - Alcohol & Phenol

  44. Reactions • Dehydration  alkenes • With HX  alkyl halides • With Tosylates • Oxidation - 1o, 2o, & 3o • Protection of alcohol Chapter 17 - Alcohol & Phenol

  45. aldehyde Pyridinium chlorochromate carboxylic acid (an aldehyde may be an intermediate but usually can’t be isolated.) Oxidation - Primary Alcohol Chapter 17 - Alcohol & Phenol

  46. Oxidation - Secondary Alcohol Chapter 17 - Alcohol & Phenol

  47. Oxidation - Tertiary Alcohol No Reaction Chapter 17 - Alcohol & Phenol

  48. Reactions • Dehydration  alkenes • With HX  alkyl halides • With Tosylates • Oxidation - 1o, 2o, & 3o • Protection of alcohol Chapter 17 - Alcohol & Phenol

  49. Protection of Alcohol “It often happens, particularly during synthesis of complex molecules, that one functional group in a molecule interferes with an intended reaction on a second functional group elsewhere in the same molecule.” - p 682. Chapter 17 - Alcohol & Phenol

  50. Triethylamine Trimethylsilyl (TMS) ether Chlorotrimethylsilane TMS ether ROH is now blocked or protected!!! Chapter 17 - Alcohol & Phenol

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