Thu January 27, 2011 By: Pratik Sethi

GIVE REASON, WHY p-bromo phenol is a major product while o-bromophenol is a minor product when phenol is treated with bromine in carbon tetrachloride. dont we get m-nitrophenol in this reaction?

Expert Reply
Thu January 27, 2011
Dear Student
In a non-polar solvent CCL4,  the ionization of phenols is greatly supprressed. So, the oxygen of OH group donates electrons to benzene ring only to a small extent and consequently the ring is activated only slighlty and hence only monosubstitution occurs. further because of steric hindrance at ortho-position the para substittuion product usually predominates.
Meta substitution does not occur because –OH  group is a +R group and tend to increase the electron density only on the ortho and para carbon making these positions vulnerable to the electrophilic attack.
We hope that clarifies your query.
Home Work Help