question_answer 27)

Explain why is ortho nitrophenol more acidic than orthomethoxyphenol? (i) electron withdrawing group, -electron releasing group, (ii) Presence of electron withdrawing group increases the stability ofphenoxide ion while presence of electron releasing group decreasesits stability. (iii) Higher is the stability of phenoxide ion formed, more is the acidiccharacter.  

Answer:

Nitro  group is electron withdrawing whereas methoxy group is electron releasing in nature, o-nitrophenol producesions easily but methoxyphenol does not. This is becauseo-nitrophenoxide ion is stabilised due to resonance. This is not true witho-methoxyphenoxide ion. The two negative charges repel each otherthereby destabilising it.   Note Also give resonating structures of o-nitrophenoxide ion for Q. 8intext questions.