Salicylic acid

Salicylic acid, or 2-hydroxybenzoic acid, is a useful chemical with the formula C7H6O3. It's commonly used as a treatment for various skin disorders and a preservative for food. Salicylic acid is also a valuable precursor. It can be used to prepare salicylate esters such as oil of wintergreen. It can be used to prepare salicylamide or it can be decarboxylated to phenol, which in turn can be used to make bisphenol compounds, phenyl esters and picric acid.

It can be made by hydrolyzing aspirin. I tried this myself.

I started with 23g of pure acetylsalicylic acid in a 1000ml flask. To this I added 11g of sodium hydroxide (an excess is best). I then slowly added 400ml of water to the mixture. A vigorous reaction was obsverved. The mixture was then gently heated without boiling for 8 mins and then filtered. The clear, slightly yellow filtrate was transferred to a flask and 33% hydrochloric acid was added slowly. Immediately a white precipitate of salicylic acid formed. I kept adding the acid until no more precipitate was observed forming.

I collected salicylic acid via filtration and washed it a few times with cold water then dried it.
The experimental yield was higher then the theoretical yield. So obviously the product still contains a bit of water.

C9H8O4 + 3 NaOH = C7H4Na2O3 + C2H3NaO2 + 2 H2O