The purpose of this lab was to help us the student become more familiar with the effect of aspirin synthesis. Aspirin was prepared from salicylic acid and acetic anhydride, using either an acidic or a basic catalyst.
0.69g of salicin acid was placed in 1.5mL of acetic anhydride in a microwave GlassChem Vessel. Sodium carbonate was added as the catalyst. The initial reaction mixture generally forms a slurry, after microwave irradiation, it will become a homogenous solution. The subsequent formation of solids indicates the presence of the desired product.
The microwave tube was placed into the turntable and it was secure. The instructor placed the turntable into the MARS microwave reactor when all of the tubes are secured. The microwave reactor will then be set to 80°C and ten minutes of reaction time.
When the microwave reaction cycle was complete, the tube was remove from the turntable, and it was stand in the beaker for easy transport, as the tube cools, the acetylsalicylic acid began to crystallize from the reaction mixture. Once the tube has reached room temperature, continue cooling in ice bath for 10 minutes, after crystal formation is complete, 10mL of cold water was added to the vessel and stir thoroughly, the product was collected by vacuum filtration, and washed twice with 2ml of cold water.
Ferric chloride test was used to look for the presence of phenols and showed a positive result if there is any unreacted salicylic acid present in the product, a small test tubes were obtained, 0.5 mL of water was added to each test tube. A small amount of salicylic acid was dissolved in the first test tube and the same amount of the product in the second test tube. The third test tube contains the solvent and was used as the control. One drop of 1% ferric chloride solution was added to each tube, shake well and color was noted.
Melting point: 107- 110°C
Percent yield: 87.78%