Isolation of Aspirin

• Tear pH paper into small squares (conserve!)

• Determine the pH of the K2HPO4 – ASP AQ solution

  • Dip a stir rod into the solution then tap it on a small piece of pH paper on a watch glass

• Obtain 10 mL of 6 M HCl in a labeled test tube - slowly add drop-wise to the ASP AQ solution

  • Swirl solution and take pH readings every 5-10 drops, until the solution is acidic (pH 2 or less)

  • Re-label the vial (Acidic ASP AQ)

A significant amount of ASP should precipitate, creating an opaque solution – collect the product by vacuum filtration:

• Pre-weigh a filter paper

• Transfer the solution to the Buchner funnel & allow the solid to dry with the vacuum on for 10-15 minutes

*Product loss: subtract 1 mg from ASP