In situ infrared spectroscopic studies of the Friedel–Crafts acetylation of benzene in ionic liquids using AlCl3 and FeCl3

Abstract

In situ infrared spectroscopic studies have revealed that the mechanism of the Friedel–Crafts acetylation of benzene is exactly the same in ionic liquids as in 1,2-dichloroethane. The reaction of acetyl chloride with benzene in the presence of MCl₃ (M = Al or Fe) in the ionic liquid 1-butyl-3-methylimidazolium chloride, ([bmim]Cl), leads to the formation of several key intermediates including the MCl₃ adducts of the acetyl chloride, the acetylium ion [CH₃CO]⁺[MCl₄]⁻, and the final product, the MCl₃ adduct of acetophenone.