Question

Arrange the following compounds in increasing order of reactivity towards nucleophilic substitution :

Answer 1

The reactivity of aryl halides towards nucleophilic substitution increases if any electron withdrawing group,such as $N{O}_2$ is bonded to the benzene ring at the ortho and para position.

In chlorobenzene, no EWG present. So, it is least reactive.

In o-nitrochlorbenzene, one EWG is present in the ortho position.

In o,p-dinitrochlorobenzene, two nitro groups present. So, it is more reactive than o-nitrochlorbenzene.

In trinitrochlorobenzene, three EWG ($N{O}_2$) present. So, it is most reactive among all the compounds.