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1. Conversion of alcohols to alkyl tosylates:
TsCl, pyridine
Poor leaving group is converted to a good leaving group:
Retention of configuration.
C-O bond remains intact.
Chapter 9: Ethers Review
1. Classification of ethers
2. Nomenclature of ethers
Give the common name for the following alcohols.
Chapter 9: Alcohols Review
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Give the IUPAC name for the following alcohols.
3. Preparation of ethers (Williamson’s ether synthesis)
SN2 reaction between an alkoxide and an alkyl halide.
Alkoxides can be prepared by deprotonation of alcohols.
For unsymmetrical ethers, two pathways are possible.
In some cases, one pathway is preferred over other.
Show two routes to synthesize ethyl isopropyl ether using Williamson’s ether synthesis. Which route is preferred?
How will you synthesize methyl phenyl ether?
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4. Reaction of ethers with strong acid
Poor leaving group renders them unreactive.
Strong acids (HBr or HI) can convert poor leaving group in a good leaving group.
Both C-O bonds are cleaved and two alkyl halides are formed.
What alkyl halides are formed when following ethers are treated with excess HX?
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Chapter 9: Epoxide Review
1. Epoxide structure
Cyclic ethers with three membered rings.
Highly reactive.
2. Preparation of epoxides
Prepared from alkenes using a two-step strategy.
Convert alkenes to bromohydrin, then reaction with a strong base.
Show synthetic strategy to prepare the following epoxide.
3. Reactions of epoxides with strong nucleophiles.
The nucleophile opens the ring from the back side attack. (SN2 followed by protonation)
The nucleophile attacks at the less substituted carbon atom in an unsymmetrical epoxide.
