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EAS:Friedel-Crafts Alkylation Mechanism definitions

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  • Friedel-Crafts Alkylation
    A process where an alkyl group is introduced to an aromatic ring using an alkyl halide and a Lewis acid catalyst.
  • Alkyl Halide
    A compound containing an alkyl group bonded to a halogen, serving as the alkyl source in this reaction.
  • Lewis Acid
    A substance, such as AlCl3, that accepts electron pairs to facilitate carbocation formation.
  • Carbocation
    A positively charged carbon species with an empty p orbital, acting as a key intermediate and electrophile.
  • Electrophile
    A species that seeks electrons, often generated by the interaction of an alkyl halide and a Lewis acid.
  • Sigma Complex
    An intermediate where the aromatic ring forms a new single bond with the alkyl group, temporarily disrupting aromaticity.
  • Resonance Structure
    Alternative depictions of electron distribution in intermediates, especially in the sigma complex.
  • Catalyst
    A substance that speeds up a reaction without being consumed, such as AlCl3, which is regenerated at the end.
  • Carbocation Rearrangement
    A shift of hydride or alkyl groups to form a more stable carbocation, often necessary with primary alkyl halides.
  • Primary Carbocation
    A carbocation attached to only one other carbon, highly unstable and rarely observed in this mechanism.
  • Secondary Carbocation
    A carbocation bonded to two other carbons, more stable than a primary carbocation and often formed via rearrangement.
  • Aromatic Ring
    A cyclic, planar structure with delocalized electrons, such as benzene, that undergoes alkylation in this reaction.
  • Beta Elimination
    A step where a proton is removed from the sigma complex, restoring aromaticity and completing the reaction.
  • Alkylation
    The introduction of an alkyl group onto an aromatic ring, resulting in a substituted benzene product.
  • AlCl3
    A common Lewis acid catalyst used to generate the active electrophile in Friedel-Crafts alkylation.