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15.5: SN2 Reactions of Allylic Halides and Tosylates

  • Page ID
    183053
  • SN2 Reactions of Allylic Halides and Tosylates

    Allylic halides and tosylates are excellent electrophiles for bimolecular nucleophilic substitution reactions (SN2). 

    ch 16 sect 5 example 1.png

    They exhibit faster SN2 reactivity than secondary alkyl halides because the bimolecular transition state is stabilized by hyperconjugation between the orbital of the nucleophile and the conjugated pi bond of the allylic group as shown in the diagram below.

    allylic sn2 hyperconjugation.jpg

    Exercise

    6.  Arrange the compounds 3-bromopentane, bromobenzene, and 3-bromo-1-propene in order of decreasing SN2 reactivity using their bond-line structures.

    Answer

    6.

    ch 16 sect 5 exercise 6 solutioin.png

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