PROCEDURE
- Weigh out 3.0 g of salicylic acid and place in a 250 ml Erlenmeyer flask.
- Measure out 6.0 ml of acetic anhydride and add this to your flask. Be sure to do this in the hood and wear your goggles..
- Carefully add 5 to 10 drops of 85% phosphoric acid, a catalyst, to the flask and swirl to mix everything thoroughly.
- Under the hood, heat the mixture for about 10 min. in a beaker of warm water (70-80 degC).
- After heating, cautiously add 20 drops of distilled water.
- Next add 20 ml of distilled water and cool in an ice bath. You can do this at your bench. If crystals do not appear, you can scratch the walls of the flask with a stirring rod to induce crystallization.
- Vacuum filter the solid aspirin. Wash the crystals with 2-3 ml of chilled water. The liquid is mostly water and can be washed down the sink. Allow the air to be drawn through the solid and filter paper for several minutes. Save your solid in an envelope; calculate the percent yield and melting point range the following week.
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