question_answer

Which one is least reactive towards nucleophilic substitution reaction?

A)  o-aminochlorobenzene

B)  Chlorobenzene

C)  o-nitrochlorobenzene

D)  2, 4-dinitrochlorobenzene

Correct Answer: A

Solution :

                                                          Aryl halides are less reactive towards nucleophiiic substitution reactions because C?X bond in them has double bond character due to conjugation between lone pair of halogen and benzene. Due to this following resonating structures are formed. Due to presence of such double bond character aryl halides show nucleophiiic substitution reactions with difficulty. However, aryl halides can be made to undergo nucleophiiic substitution by the presence of electron withdrawing groups (such as \[-N{{O}_{2}}\]) at the o and p-positions to the nuclear halogen, But in the presence of electron donating groups (such as \[-N{{H}_{2}}\]) at o or p-position, it is very difficult to show nucleophiiic substitution reaction. Therefore, is least reactive towards nucleophiiic substitution reaction.