- Chapter 9 covers reactions of alcohols, ethers, epoxides, and thiols including substitution, elimination, rearrangement, and naming reactions. - Key reactions include Williamson ether synthesis, SN1/SN2 reactions of alcohols to form ethers/alkyl halides, acid or base catalyzed dehydration of alcohols, and opening of epoxides and cyclic ethers via nucleophilic substitution. - Proper identification of reaction type as SN1, SN2, E1 or E2 is important to determine reaction mechanism and product.

1. Chapter 9 Review
HELLO EVERYONE AND WELCOME TO ORGANIC CHEMISTRY THE
ONLY CLASS THAT MAKES TALKING ABOUT ALCOHOL BORING

2. Review of Chapter 7: Sn1
•Sn1
• Involves carbocation intermediate
• Racemic mixture as product
• Weak nu:
• Rate increases with increasing number of substituents
• Mechanism

3. Review of Ch.7: Sn2
•Inversion of stereochemistry
•1 step
•Need a strong nucleophile
•Less R groups the better
•Mechanism

4. Whats what

5. Naming Alcohol
•Take off “–e” ending an replace it with “–ol”
•Prior to suffix –ol include the position of the hydroxy
•Just like in life, alcohol takes top priority, for now
•If on a ring, DO NOT NUMBER THE ALCOHOL
•2 alcohols? Use suffix -diol

6. Practice

7. Naming Ethers
•Common names
• Substituent 1 + substituent 2 + “ether”
• Alphabetize
•IUPAC
• Smaller group gets named as an alkoxy
• For example a methyl group on an ether is called methoxy
• The longer chain gets named as the parent

8. Practice (both common and IUPAC)

9. Naming Epoxides (epoxy alkanes)
•Numbering is really weird.
• 1st number, 2nd number (i.e. 2,3)
•If stereochemistry is indicated uses prefixes: cis or trans accordingly
•Use –epoxy to name the functional group

10. Naming Epoxides (other 2 methods)
•Alkene oxide
• Name of alkene + oxide
•Oxirane
• When numbering; Oxygen gets 1 and then go around the cyclic structure

11. Practice

12. Physical properties
•For solubility questions, use 5 carbon rule
•As R groups increase, ability to H bond decreases
•Alcohols have really strong hydrogen bonds
•Ethers and epoxides have dipole-dipole interaction

13. practice

14. Chapter 9 In A Nutshell
•The first step is to make OH a good leaving group
•The next step is generally going to be Sn1, Sn2, E1, E2
•The key to this chapter is going to be figuring out what
the second step is
•If you don’t know, use rules from Chapters 7 and 8 to
give it your best guess
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15. Carbocation rearrangement
•There are 3 I know of
•2 you need to know
• 1,2 hydride shift
• 1,2 methyl shift
•These will occur only if there is a carbocation formed (E1, Sn1)
•It will only rearrange if carbocation can move to be more stable

16. Overview

17. Preparation reactions
•Williamson ether synthesis
• Sn2 reaction involving an alkyl halide and an alkoxy nucleophile
• We use the exact same process for sulfide production
• Mechanism
•Preparation of epoxides
• Intramolecular nucleophilic attack
• We need a base to make an alcohol a better nucleophile

18. Practice (I also like 9.10)

19. Dehydration Reactions
•This slide only applies to the H2SO4 and TsOH reactions
•If primary alcohol; E2
•If secondary or tertiary alcohol; E1
•Remember your chapter 8 rules for reaction rate

20. practice

21. practice

22. Dehydration with Phosphoryl Chloride
•POCl3 in pyridine
•POCl3 makes OH a good leaving group
•Pyridine acts as a base so we can eliminate

23. Mechanism for POCL3

24. Conversion of Alcohol To Alkyl Halide
•HX where X=Br
•HCl with ZnCl2
•Cl needs the Lewis acid, ZnCl2, because it is a weaker Nu:
•SOCl2 (Sulfur is in same family as oxygen)
• Mechanism
•PBr3 (phosphorus is in same family as Nitrogen)
• Mechanism

25. Mechanism (SOCl2)

26. Mechanism (PBr3)

27. Mechanism (HX)
•The first step is protonation of OH to form water
•Second step is Sn1 or Sn2
•For HCl, there is a intermediate involving ZnCl2, but don’t worry about it.

28. practice

29. Practice

30. Tosylates
•Use alcohol and TsCl
• This forms a good leaving group
•Mechanism ( the second step can be anything)

31. Practice
I also like 9.27

32. Thiols
•Basically big alcohols
•Made of sulfur and not oxygen
•We call them mercapto groups
•We name them pretty much the same as alcohol
• We use suffix -thiol

33. disulfides
•I do not believe we need to know the mechanisms

34. Opening Up Rings
•Attack from the least substituted side
• The product should be anti periplanar
• Its just an Sn2 followed by protonation
•We can also protonate first if there is an acid catalyst
• If this is the case we attack at the more substituted side
• We attack at this side due to charge stabilization

35. practice