Chapter 16: Ethers, Epoxides and Sulfides

Williamson Ether Synthesis

Reaction type: Nucleophilic Substitution (S_N2)

Summary

• Reagents : typically use Na metal as the base to generate the alkoxide then add the alkyl halide.
• Since the reaction is S_N2, the halide should be methyl or primary.
• Alkoxide character (primary, secondary or tertiary) is less important.
• This reaction is suitable for either symmetrical or unsymmetrical ethers.
• The method could also be used for cyclic ethers.

QUESTIONS

	What reaction is likely to interfere if the halide is tertiary ?	ANSWER
	Can you write a balanced equation for the reaction of sodium metal with the alcohol ?	ANSWER
	What is the oxidation state and charge of the sodium metal ?	ANSWER
	What makes the methyl and primary halides most suitable ?	ANSWER

Related Reactions

• Ether synthesis via Alcohol condensation
• Substitution Reactions of Alkyl Halides

MECHANISM OF THE WILLIAMSON ETHER SYNTHESIS
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.

© Dr. Ian Hunt, Department of Chemistry