The major reason haloarenes are less reactive than haloalkanes and haloalkenes is the resonance stabilization of the aryl ring. For example, in C₆H₅-Cl, the electron pairs on halogen atom are in conjugation with ϖ-electrons of the ring. Due to resonance, the C—Cl bond acquires a partial double bond character, making it less reactive to nucleophilic substitution than haloalkanes and haloalkanes.