Question

What is Effect of Substituents on Phenols?

Answer

The presence of electron withdrawing groups like -NO2, -CN etc. on the benzene ring stabilises the phenoxide ion by the dispersal of negative charge, thereby, increasing the acidic strength of phenol. Whereas, presence of electron donating groups like -CH3 etc. on the benzene ring destabilises the phenoxide ion by increasing the negative charge, thereby, decreasing the acidic strength of phenol.