|Chapter 17: Aldehydes and Ketones. Nucleophilic Additionto C=O|
(review of Chapter 12)
Reaction type: Electrophilic Aromatic Substitution
|MECHANISM FOR THE FRIEDEL-CRAFTS ACYLATION OF BENZENE|
The acyl halide reacts with the Lewis acid to form a a more electrophilicC, an acylium ion
The π electrons of the aromatic C=Cact as a nucleophile, attacking the electrophilic C+. This step destroysthe aromaticity giving the cyclohexadienyl cation intermediate.
Removal of the proton from the sp3 C bearing the acyl- groupreforms the C=C and the aromatic system, generating HCl and regeneratingthe active catalyst.
|© Dr. Ian Hunt, Department of Chemistry, University of Calgary|