It was proposed that resonance delocalization of an oxygen non-bonded electron pair into the pi-electron system of the aromatic ring was responsible for this substituent effect. 4-nitrophenol is a member of the class of 4-nitrophenols that is phenol in which the hydrogen that is para to the hydroxy group has been replaced by a nitro group.

(ii) Phenol is an aromatic alcohol in which the group is directly attached to hybridized carbon of benzene ring. group is an electron donating group. There are four resonating structures of phenol. Similarly, in case of phenol the lone pair on oxygen participates in delocalization with electrons of benzene ring system and the negative charge will delocalized on -ortho and -para position. Resonance structures of phenol Notice that three of the four contributing structures possess a positive charge on the oxygen atom of the molecule. In these resonating structures, positive and negative charges are present together. Thus, the true hybrid structure must possess a … A similar set of resonance structures for the phenolate anion conjugate base appears below the phenol structures. Thus, energy must be provided to separate these opposite charges.The structure of phenol should contain more energy.
It has a role as a human xenobiotic metabolite and a mouse metabolite.