Question

Arrange the following in the increasing order of acidity.

• A. Phenol
• B. Methanol
• C. 4-Nitrophenol
• D. Isopropanol
• E. Tert-butanol

Answer 1

Acidity of aliphatic alcohols is in the order: primary>secondary>tertiary. This is because, the electron donating alkyl groups on carbon, attached to the -OH group increases the electron density on oxygen atom and hence reduces the polarity of O-H bond. This decreases the acid strength of secondary and tertiary alcohols.
Obviously, nitrophenols are more acidic than phenols due to the electron withdrawing nitro group.