Question

Out of chlorobenzene and 2,4,6-trinitrochlorobenzene, which is more reactive towards nucleophilic substitution and why?

Hint:

Electron-withdrawing groups such as nitro ($\text{NO}_2$) increase the reactivity of aromatic compounds in nucleophilic substitution reactions by destabilizing the carbon-halogen bond.

Answer 1

2,4,6-Trinitrochlorobenzene is more reactive towards nucleophilic substitution because the nitro ($\text{NO}_2$) groups present on the benzene ring are electron-withdrawing in nature. These groups pull electron density away from the ring, making the carbon-chlorine bond weaker and easier to break, facilitating nucleophilic attack. In contrast, chlorobenzene does not have such electron-withdrawing groups, making it less reactive towards nucleophilic substitution.