The chemical equation for the synthesis of aspirin is C7H6O3 + C4H6O3 –> C9H8O4 +C2H4O2, which is a reaction of salicylic acid with acetic anhydride in the presence of phosphoric acid. The byproduct is acetic acid.
Adding cold water stops the reaction, and the products are filtered, yielding aspirin. Once aspirin is synthesized, it needs to be purified, and an estimation of its purity should be performed.
Aspirin, or acetylsalicylic acid, is one of the oldest and most common medications worldwide. It is used to treat pain, reduce fever, and to decrease the aggregation of platelets, such as to decrease blood clotting.