Question

Assertion :Following reaction fail to produce benzoic acid Reason: Aryl halides do not usually undergo $S_{N}2$ reaction

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is D Assertion is incorrect but Reason is correct

Aryl halides are relatively unreactive toward nucleophilic substitution reactions. This lack of reactivity is due to several factors. Steric hindrance caused by the benzene ring of the aryl halide prevents $S_{N}2$ reactions. Likewise, phenyl cations are unstable, thus making $S_{N}1$ reactions impossible. In addition, the carbon halogen bond is shorter and therefore stronger in aryl halides than in alkyl halides. The carbon halogen bond is shortened in aryl halides for two reasons. First, the carbon atom in aryl halides is $s{p}^2$ hybridized instead of $s{p}^3$ hybridized as in alkyl halides. Second, the carbon halogen bond has partial double bond characteristics because of resonance.
Because three of the four resonance structures show a double bond between the carbon and halogen atoms, the hybrid structure must have double bond character.