The Friedal-Crafts Reaction (Alkylation, Acylation through EAS)
The Friedal-Crafts reactions are a set of reactions used to attach groups to an aromatic ring. Alkylation and acylation can be successfully done through electrophilic aromatic substitution, paying close attention to electron donating and withdrawing groups.
In alkylation, the product will be more nucleophilic than the reactant due to addition of electron donating groups (alkyl groups) thus multiple alkylations may occur. (Why is alkyl an electron donating group? Click here to see a previous post about alkyl groups.)
On the other hand, acylation will not occur multiple times because the product is less reactive than the reactants due to the addition of an electron withdrawing group (an acyl group).
* If the chlorine is not on a tertiary carbon, there is a possibility it will rearrange to form a more stable carbocation.