Question

The major product in the following reaction is $Ph-Cl+B{r}_2\stackrel{\text{Anhydrous}FeB{r}_3}{\to }$ Product

• A. o-bromochlorobenzene
• B. p-bromochlorobenzene
• C. m-bromochlorobenzene
• D. 2, 4, 6-tribromochloro benzene

Answer 1

The correct option is B p-bromochlorobenzene

Since, $C{l}^{-}$ group attached to benzene is ortho and para directing, so it forms $o-$ and $p-$bromochlorobenzene products in electrophilic substitution reaction of chlorobenzene but the major product will be para product because ortho is disfavourd due to inductive effect and steric hindrance.

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

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

As the size of electrophile increases, percentage of para product increases because $E^{+}$ and Y are apart so there is negligible interaction betweem them.​


The % of ortho and para product formed is depicted below in table with various electrophiles.