Question

Arrange the following compounds in the increasing order of their acidic strength:
3,5-dinitrophenol, 4-methylphenol, phenol, 2,4,6-trinitrophenol.

Hint:

Electron-withdrawing groups increase acidity by stabilizing the negative charge on the conjugate base.

Answer 1

The order of acidity is as follows: 2,4,6-trinitrophenol>3,5-dinitrophenol>phenol>4-methylphenol.
The nitro groups on the phenol ring increase the electron-withdrawing effect, making the phenol more acidic. 2,4,6-Trinitrophenol has three nitro groups, making it the most acidic, while 4-methylphenol is the least acidic due to the electron-donating nature of the methyl group.