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Williamson Ether Synthesis

  • Page ID
    43084
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    Williamson ether synthesis is a method of preparation of ethers. It is a nucleophilic aliphatic substitution at saturated carbon in which the nucleophile is either an alkoxide ion or a phenoxide ion.

    william1.png

    • R1 = alkyl, allylic, benzylic
    • R2 = alkyl, aryl

    eg:

    william2.png

    Some symmetrical ethers can not be prepared using Williamson either synthesis because, in addition to nucleophilic aliphatic substitution, 1,2-elimination could occur between a substrate bearing beta hydrogens and an alkoxide ion, leading to an alkene as the organic product.

    eg:

    william3.png

    To prepare ether 1 using Williamson ether synthesis, a tert-butyl substrate (2) should be reacted with the tert-butoxide ion (3).

    william4.png

    Since alkoxide ions are strongly basic and since the substrate is a tertiary alkyl substrate, the major reaction between 2 and 3 would be 1,2-elimination, giving alkene 4 as the organic product.

    william5.png

    Preparation of unsymmetrical ethers using Williamson ether synthesis requires planning because, again, in addition to nucleophilic aliphatic substitution, 1,2-elimination could occur between some substrates and alkoxide ion and could be the dominant process.

    eg:

    william6.png


    Williamson Ether Synthesis is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Gamini Gunawardena via source content that was edited to conform to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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