Question

Nitration of phenols is a classic example of an electrophilic aromatic substitution reaction.

a) Why does the nitration of phenol (hydroxybenzene) proceed only in the ortho- and para-positions on the ring?

b) Draw the resonance structures that highlight the ortho- and para-directing nature of hydroxy substituents. Make sure to include the structures that showcase the movement of the charges in the ring.

Answer 1

a) in the nitration reaction, electrophile NO2+ ion generated and it's attracks on ortho and pera position on benzene ring of phenol because phenolic OH group is electron donating group increases the electron charge density at Ortho and pera position in Benzene ring so that NO2+ electrophile attract towards more electron charge density in Ortho and pera - position

Hence nitration of phenol gives Ortho and pera - substituted product.

b)

(1) H-o- G2 -он HOJ Qays= + ON=0 (no) : H Cij) OH OH H H NOL IVO2 NO₂ Ortho-position attack با H-02 H OH LNG (ortho-substituted Product) (Stablized Carbocation Jn ter midiate) (Resonance structures) III STOH H NOL OH OH ( Resonance Hybride) - NO SOH - pera - Position attacks JO2 . H NOL (stablized) H NO OH OH H (pera-substituted product) NO2 ( Resonance Stru ructures)