Question

On nitration, the major product that chlorobenzene gives is:

• A. 1-chloro-4-nitrobenzene
• B. 1-chloro-3-nitrobenzene
• C. 1, 4-dinitrobenzene
• D. 2, 4, 6-trinitrobenzene

Answer 1

The correct option is A 1-chloro-4-nitrobenzene

Since, $C{l}^{-}$ group attached to benzene is ortho and para directing, so it forms $o-$ and $p-$ chloronitrobenzene as products in electrophilic substitution reaction of chlorobenzene.
Here the major product is p-chloronitrobenzene because ortho is disfavourd due to inductive effect and steric hindrance. Hence correct option is a.

Intermediates of electrophilic substitution reaction​:
In para substituted, $E^{+}$ and Y=Cl are apart so there is negligible interaction ​

In ortho substituted, $E^{+}$ and Y=Cl are close so there is more interaction. ​

As the size of electrophile increases, percentage of para product increases because $E^{+}$ and Y=Cl are apart so there is negligible interaction betweem them.​ The % of ortho and para product formed is depicted below in table with various electrophiles.