Epoxidation

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Epoxidation of Alkene with mCPBA
6:59 — by Heath G.

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Key Questions

  • Answer:

    Asymmetric epoxidation (also called the Sharpless epoxidation reaction) is a method of preparing chiral epoxides from prochiral allylic alcohols.

    Explanation:

    It uses a catalyst containing either (+)- or (-)-diethyl tartrate to form the chiral epoxide in greater than 90 % enantiomeric excess.

    www.organic-chemistry.org

    The oxidizing agent is tert-butyl hydroperoxide.

    The catalyst is prepared from titanium tetra(isopropoxide), #"Ti"["OCH"("CH"_3)_2]_4#.

    It binds the hydroperoxide, the allylic alcohol group, and the chiral tartrate ligand through the oxygen atoms.

    A "simplified" Jmol image of the complex (below) shows how an #"O"# atom of the hydroperoxide is preferentially pointed towards one face of the alkene.

    Complex
    (Adapted from chemtube3d)

  • Answer:

    The reaction of alkenes with peroxides is often called an epoxidation reaction.

    Explanation:

    It is sometimes called the Prilezhaev reaction, after the Russian chemist who discovered it in 1909.

    The reaction involves the action of a peroxyacid with an alkene to form an epoxide.

    www.organic-chemistry.org

    You can read more about this reaction in the Socratic answer to What is epoxidation of alkenes?.

  • Answer:

    Well, you take an olefin, and make a three-membered ring...........

    Explanation:

    And from the three-membered epoxide ring, once ring-opened, you can get TWO functionalized sites.

    And these days, epoxidation is not only highly chemically efficient and selective, it is increasingly highly stereochemically selective. Look up #"Sharpless peroxidation"#, which won for its inventor, Barry Sharpless, a Nobel prize in 2001.

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