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Limitations of Friedel-Crafts Alkyation quiz Flashcards

Limitations of Friedel-Crafts Alkyation quiz
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  • What are the limitations of Friedel-Crafts alkylation with vinyl or aryl halides?
    Friedel-Crafts alkylation does not work with vinyl or aryl halides because the resulting carbocations are too unstable to react.
  • Why do aniline derivatives interfere with Friedel-Crafts alkylation?
    Aniline derivatives form a complex with the Lewis acid catalyst, deactivating it and preventing the alkylation reaction.
  • What is a major issue with carbocations in Friedel-Crafts alkylation?
    Carbocations can rearrange, leading to unexpected products and reducing the predictability of the reaction.
  • How does Friedel-Crafts acylation differ from alkylation in terms of carbocation rearrangement?
    Friedel-Crafts acylation forms an acylium ion that does not rearrange, making the reaction more predictable than alkylation.
  • What is the effect of electron-donating groups in Friedel-Crafts alkylation?
    Electron-donating groups activate the benzene ring, leading to polysubstitution and making the reaction difficult to control.
  • Why is Friedel-Crafts acylation preferred over alkylation for controlling substitution on benzene rings?
    Acylation introduces an electron-withdrawing group, reducing further reactivity and preventing polysubstitution.
  • What happens when an electron-withdrawing group is added to a benzene ring in Friedel-Crafts acylation?
    The electron-withdrawing group decreases the reactivity of the benzene ring, preventing further substitution reactions.
  • How can acetylation be used to prevent the deactivation of the Lewis acid catalyst by aniline derivatives?
    Acetylation of aniline derivatives reduces their basicity, preventing them from forming a complex with the Lewis acid catalyst.
  • What is the main advantage of using Friedel-Crafts acylation over alkylation?
    Friedel-Crafts acylation avoids carbocation rearrangements and controls the degree of substitution, making it a safer and more predictable reaction.
  • Why is polysubstitution undesirable in Friedel-Crafts alkylation?
    Polysubstitution leads to multiple R groups on the benzene ring, complicating the reaction and making it difficult to achieve the desired product.