The chloromethylated polystyrene resin used for Merrifield solid-phase peptide synthesis is prepared by treatment of polystyrene with chloromethyl methyl ether and a Lewis acid catalyst. The reaction involves the following steps: Reaction of the ether with the Lewis acid to form cation 1; Electrophilic aromatic substitution to form resonance stabilized cation 2; Deprotonation yields aromatic ether 3; Protonation to form protonated ether 4; Displacement by chloride ion to form the final product. Write out the mechanism on a separate sheet of paper and then draw the structure of the resonance contributors of the resonance stabilized cation 2.