Friedel crafts Reaction between benzene and acetic anhydride in the presence of anhydrous $\mathrm{A}\mathrm{l}\mathrm{C}{\mathrm{l}}_3$ yields acetophenone. Polyacylation in Friedel craft reaction is not possible because acyl group is a deactivating group and only mono substitute product is formed therefore, during Friedel crafts alkylation carbocation formed so rearrangement of carbocation is possible, and it is weak electrophile then acylinium ion.