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CH3CH2-OH ---(H+)--->
- CH3CH2-O(+)H2 --- CH3CH2-OH ---->
- CH3CH2-O-CH3CH2 + H(+)
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Ether Synthesis: Williamson
- R-OH + NaH ---> RO(-)Na(+) + H2
 - , where X: Cl, Br, I, OTos
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What carbon should the leaving group be on in a Williamson reaction?
The least substituted carbon
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Ether Synthesis: Alkoxymercuration
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What is a limitation of alkoxymercuration in ether synthesis?
Ditertiary ethers cannot be formed due to steric hindrance.
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Ether Reactions: Cleavage
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What acids can be used to cleave ethers?
HBr and HI. NOT HCl
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An ether with only primary and secondary alkyl groups undergo cleavage by what type of substitution and on which alkyl group?
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An ether with a tertiary, benzyllic, or allylic alkyl group usually undergoes cleavage by what mechanism?
Sn1
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Ether Reactions: Claisen
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Claisen rearrangement is specific to what type of ether?
Allyl aryl
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mCPBA
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MMPP
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In acid-induced opening of expoxides with HBr, there is a high degree of Sn___ character which leads to OH being formed on the more stable ___, i.e. ___.
1, cation, tertiary
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- Can use OH or CH3MgBr instead of RO-
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What is the importance of Crown ethers?
- They solvate metal cations such as K+
- Enhances Sn2 reactivity of an anion
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What is a mercaptan?
A Thiol
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What is the most striking characterestic of a thiol?
The horrible odor - skunk, onion, garlic, additive for natural gas.
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Thiols are like alcohols, but are ____ bases and ____ nucleophiles.
stronger, better
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A sulfide is like an analog of what?
An ether. Sulfide: R-S-R
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Thiol Synthesis
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Thiol Synthesis
- ---OH(-)--->
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Oxidation of Thiols
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Unlike dialkyl ethers, dialkly sulfides are ___ nucleophiles that react with primary alkyl halides by an ___ mechanism to give ____.
good, Sn2, sulfonium ions S+(R)3
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Oxidation of Sulfides
- If R=R'=CH3, product is DMSO
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Oxidation of Sulfides
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What makes ethers good solvents?
- Polar
- Aprotic
- Relatively inert
- Cheap
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What are the cons of ethers as a solvent?
Flammable/explosive
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Ethers are prepared by either ___ which involves ___ reaction of an alkoxide with a primary alkyl halide, or the ___ reaction which involves Markovnikov addition of an alcohol to an alkene.
Williamsom ether synthesis, Sn2, alkoxymercuration
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Ethers are inert to most reagents but react with ___ to give cleavage products.
strong acids
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Cleavage of ethers takes place by an ___ mechanism at the ___ highly substituted site if only ___ alkyl groups are bonded to the either oxygen, but by an ___ mechanism if one of the alkyl groups is ___.
Sn2, less, primary and secondary, Sn1 or E1, tertiary
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___ ethers undergo Claisen rearrangement to give ___.
Aryl allyl, o-allylphenols.
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Due to ___, epoxides undergo a ___ reaction with both acids and bases.
strain, cleavage
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In epoxides, acid cleavage of the C-O bond at the ___ highly substituted site occurs if both epoxide carbons are ___, but occurs at the ___ highly substituted site if one of the epoxide carbons is ___.
less, primary or secondar, more, tertiary
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Base-catalyzed epoxide ring-opening occurs by ___ reacition of a ___ at the ___ hindered epoxide carbon.
Sn2, nucleophile, less
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Thiols, the sulfur analogs of ___, are usually prepared by ___ reaction of ___ with thiourea.
alcohols, Sn2, an alkyl halide
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Mild oxidation of a thiol yields a ___, and mild reduction of a ___ gives back the thiol.
disulfide, disulfide
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Sulfides are prepared by an ___ reaction between a ___ and a ___.
Sn2, thiolate anion, primary or secondary alkyl halide
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Sulfides are much more ___ than ethers and can be oxidized to ___ and ___.
nucleophilic, sulfoxide, sulfones
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Sulfides can be alkylated by reaction with ___ to yield ___.
a primary alkyl halide, sulfonium ions.
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