question_answer 28)

Explain how does the —OH group attached to a carbon of benzene ring activate if towards electrophilic substitution? Resonance effect clue to —OH group.  

Answer:

In the presence of attacking electrophile, ?OH group exerts+R effect on the benzene ring. So, electron density in the ring increasesparticularly at the ortho and para positions. When an electrophileattacks, substitution takes place readily at these (oandp-) positions.