Question

why haloarenes are less reactive than haloalkane

Answer 1

here is u r answer

Haloarenes are very much less reactive than haloalkanes towards nucleophilic substitution reactions. The lone pair of halogen atom is delocalized in the phenyl ring and development of partial double bond character in C—X bond,making it morestrong. ... Well, there are multiple reason for haloarenes being less reactive.

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Answer 2

Due to phenyl cation is not resonance

OR

Haloarens are resonance stabilised

with carbon double bond .