Question

Explain the mechanism Of electrophilic aromatic substitution reaction of phenol and also explain why OH group in panel act as Ortho & para director

Answer 1

Answer on Question #72511, Chemistry / Organic Chemistry

Question:

Explain the mechanism of electrophilic aromatic substitution reaction of phenol and also explain why OH group in phenol acts as ortho & para director.

Answer:

OH group in phenol has strong positive mesomeric effect:

As you can see, **ortho and para positions** have partial negative charge, and therefore electrophiles attack **them**.

Mechanism of the reaction (for ortho position):

At the first step an electrophile (E⁺) attacks the aromatic ring and at the second step the intermediate complex looses proton (H⁺) and forms the product. Please see the scheme below. Also note that intermediate complex has four tautomeric forms.

For para position the mechanism is absolutely the same.