Aspirin synthesis

1. Synthesis of acetylsalicylic acid

a) Place salicylic acid (4.6 g) and acetic anhydride (7.0 cm³, 7.5 g) in a 100 cm³ round-bottomed flask. Swirl to dissolve, warming slightly if necessary.

b) Add concentrated sulfuric acid (3 drops), fit a plastic stopper and swirl the flask gently to mix the contents.

c) Immerse the flask to approximately half its depth in a water bath containing water kept at 60-65^oC. Do not overheat the water.

d) Swirl the contents of the flask gently to ensure complete dissolution of the salicylic acid.

e) Remove the flask from the water bath after fifteen minutes and allow to cool to room temperature.

f) Remove the stopper and whilst stirring the flask content gently with a glass rod add water (75 cm³) as a gentle stream.