Aryl halides exhibit lower reactivity in nucleophilic substitution due to the resonance effect, which imparts partial double bond character to the C—X bond, making bond cleavage more challenging compared to haloalkanes.
Why are aryl halides less reactive towards nucleophilic substitution compared to haloalkanes?
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Aryl halides are less reactive towards nucleophilic substitution compared to haloalkanes due to the resonance stabilization in the benzene ring. The aromaticity of benzene imparts extra stability through resonance, which involves the delocalization of electrons across the ring. This stability hinders the attack of nucleophiles at the halogen atom. In contrast, haloalkanes lack this resonance stabilization, making them more susceptible to nucleophilic substitution reactions. The electron-rich nature of the benzene ring in aryl halides prevents easy access to the halogen, reducing the reactivity towards nucleophilic substitution reactions compared to their aliphatic counterparts.