4 g of picric acid is dissolved in 90 mL of 95 ° C water, then 1.3 g of potassium hydroxide is added with constant stirring. The solution is evaporated to a volume of 40 mL and then allowed to cool to 5°C, filtered and washed with 50 mL of ice-cold water. The product may be recrystallized from hot water.
Desolvation of the picric acid
Evaporation of the basified solution
The crude product
The recrystallized product