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Chapter 15: Alcohols, Diols and Thiols |
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Williamson Ether Synthesis
Reaction type: Nucleophilic Substitution (SN2)
Summary
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Reagents : typically use Na metal as the base to generate the alkoxide
then add the alkyl halide.
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Since the reaction is SN2, the halide should be methyl or primary.
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Alkoxide character (primary, secondary or tertiary) is less important.
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This reaction is suitable for either symmetrical or unsymmetrical ethers.
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The method could also be used for cyclic ethers.
Questions:
What reaction is likely to interfere if the halide is tertiary ?
Can you write a balanced equation for the reaction of sodium metal
with the alcohol ?
What is the oxidation state and charge of the sodium metal ?
What makes the methyl and primary halides most suitable ?
Related Reactions
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MECHANISM OF THE WILLIAMSON ETHER SYNTHESIS
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The alkoxide functions as the nucleophile and attacks the electrophilic
C of the alkyl halide displacing the bromide and creating the new C-O
bond. This is an example of an SN2 reaction. |
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