# Why is oxygen absorbed in a colorless alkaline solution of pyrogallol and why does it turn dark brown?

My book says:

Oxygen is absorbed in colorless alkaline solution of pyrogallol and turns dark brown?

I'd like to know why and how.

The balanced equation describing the initial radical oxidation of pyrogallol to the quinone can be written as $$\ce{2~ pyrogallol + O_2 -> 2 ~o-quinone + 2H2O}$$