question_answer 8)

Ortho and para nitrophenols are more acidic than phenol.Draw the resonance structures of the corresponding phenoxide ions. Acidic strength depenas on the relative stabilities of correspondingphenoxide ions based on resonance.  

Answer:

(i) Phenoxide ion     (ii) o-nitrophenoxide ion     (iii) p-nitrophenoxide ion     Due to ?R effect of ? group, o- and p-nitrophenoxide ions are more stable than phenoxide ion. Consequently, both o- and p-nitrophenols are more acidic than phenol. Note Structures in boxes have negative charge on that C-atom to which electron withdrawing ? group is attached. So, these structures contribute more towards the acidic character than the others.