Acidity of alcohols

Acidity of alcohols

According to Bronsted theory, an acid is defined as a proton donor and the acid strength is the tendency to give up a proton. Alcohols are weakly acidic and their acidity is comparable with water. Except methanol, all other alcohols are weaker acid than water. The K_a value for water is 1.8 ×10^−16 where as for alcohols, the K_a value in the order 10^−18 to 10^−16.

Alcohols react with active metals such as sodium, aluminium etc… to form the corresponding alkoxides with the liberation of hydrogen gas and similar reaction to give alkoxide is not observed in the reaction of alcohol with NaOH.

2C₂ H₅ - OH + 2Na → 2C₂ H₅ONa + H₂ ↑

The above reaction explains the acidic nature of alcohols.