Question

Which of the following products predominates (major product) in the following reaction?

(A) 2-Chloronitrobenzene
(B) 3-Chloronitrobenzene
(C) 4-Chloronitrobenzene
(D) A and C both

Answer 1

Hint: Electron donating groups on the benzene ring directs the electrophiles to attack benzene at ortho and para positions. Therefore electron-donating groups on the benzene ring are called ortho and para directing groups.

Complete step by step solution:
-In the given question the reactant is chlorobenzene.
-The given reaction is the best example of the nitration reaction (electrophilic substitution reaction).
-Chlorine atom presents on the benzene ring and donates the electrons to the benzene ring and will show some resonance structures.
-The resonance structures of chlorobenzene are as follows.

-From the above resonance structures, we can easily say that chlorine is going to direct the electrophilic groups to ortho and parasites on the benzene ring.
-The coming electrophile attack at these positions.
-But due to steric hindrance at the ortho position because of chlorine, the para-product typically dominates over the ortho-substituted product.
-The halogen atom (chlorine) has -I effect because of electron-withdrawing nature.
-Thus chlorine deactivates the benzene ring. So, the electrophilic substitution reactions on chlorobenzene occur slowly but under drastic conditions when compared to benzene.
-Therefore in the given reaction 4-Chlorobenzene is the major product when compared to 2-chloro benzene.

So, the correct option is C.

Note: Because of the large number of electrons present surrounding the chlorine which is very nearer to ortho position does not favour the formation of ortho-substituted product in major amounts. So, para-substituted product forms in a major amount.