Q

Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?

13.19     Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?

In benzene, the $\pi$-electrons are delocalised above and below of the ring. Thus it is an electron rich species. In nucleophilic substitution, the attacking species is an electron-rich in nature, so it becomes challenging to attack benzene because they are repelled by benzene. On the other hand, when the attacking agent is electrophile, which is electron deficient, are easily attracted by the benzene.