Drawbacks of Friedel Craft Acylation Reaction
1) Alkylation
Branched alkyl chlorides (20 or 3o) cannot be used as a reagent in FC acylation reaction. The branched alkyl chlorides on forming acylium ion undergo the loss of CO to create a stable alkyl cation. The 20 or 3o alkyl cation reacts with benzene to form alkyl benzene.