The Williamson ether synthesis is an SN2 reaction

The Williamson ether synthesis uses a base and an alkyl halide to convert an alcohol into a symmetrical or an unsymmetrical ether. The base deprotonates the alcohol to form an alkoxide that undergoes a nucleophilic substitution (SN2) reaction with the alkyl halide, producing the ether and a metal halide.  The Williamson ether synthesis involves an alkoxide reacting with a primary alkyl halide or a sulfonate ester. 

  • Reagents: Base, Solvent (DMSO, DMF, etc.)
  • Reactant: Aliphatic/Aromatic Alcohol and Alkyl, Allyl or Benzyl Halide
  • Product: Ether
  • Type of Reaction: SN2
  • Bond Formation: R1-O-R2

Lab Tips

  • Dialkyl ethers are easily synthesized with a strong base such as NaH, KH, LHMDS, or LDA. Aryl ethers are synthesized with NaOH, KOH, K2CO3, or Cs2CO3.
  • Use of dipolar aprotic solvents minimizes dehydrohalogenation side products.
  • Tertiary or sterically hindered primary or secondary alkyl halides are prone to E2 elimination, affording an alkene product.
  • Diaryl ethers cannot be prepared from phenoxides with unactivated aryl halides. The presence of copper metal or a Cu(I)-salt catalyst can make this reaction go (Ullmann biaryl ether synthesis), or if the aryl halide is activated with a strongly electron-withdrawing substituent.
  • Alkali phenoxides may undergo C-alkylation in addition to O-alkylation.
Kürti, L., Czakó, B. (2005). Strategic Applications of Named Reactions in Organic Synthesis; Background and Detailed Mechanisms. Burlington, MA: Elsevier Academic Press.


Top Citations

Original Paper

Related Reactions

Related Compounds

  • Base
By shuhan yang


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