On Friday, February 12, 2016, approximately 25 AP Chemistry students from Forest Park High School visited Clayton State University. These AP Chemistry students, led by chemistry professors Dr. Aubrey Dyer and Dr. John Meyers of the Department of Chemistry and Physics, participated in a hands-on experiment synthesizing (or making) aspirin.
Aspirin, or acetylsalicylic acid, is one of the most widely used medicines in the world and is used to treat a plethora of issues ranging from pain to acne to heart problems. The AP Chemistry students of Forest Park High School had the opportunity to synthesize and test the quality of their own product. Before jumping in, the students began their session by reviewing and comparing the molecular structures of acetylsalicylic acid (aspirin) and salicylic acid (the starting material used to make aspirin). The students identified the differences between these two molecules to create a plan as would any synthetic chemist. Next, the students broke off into groups and began their experiments by mixing the chemicals necessary to break unwanted chemical bonds and make desired bonds with their molecules. Their synthesized product was then purified with a technique called recrystallization, in which the property of solubility is taken advantage of to isolate pure aspirin.
Once the groups finished their purification step, they each subjected their (hopefully) aspirin product, as well as salicylic acid and commercial aspirin, to a colorimetric test. This colorimetric test serves to test the quality of the product that each group made. The group correctly identified a structural motif that is present in the starting material, but not in the product, that produces a vibrant purple color when mixed with iron(III) chloride. They could see first hand how pure their product was based on the deepness of purple that they saw - the lighter (or lack) of purple color means that their product contained a larger amount of aspirin. They also learned that commercial aspirin is not made entirely of acetylsalicylic acid, but contains a small amount of salicylic acid as an impurity based on this colorimetric test.
The students combined their knowledge of chemical structure and bonding from the classroom with the laboratory techniques shown during their visit to make and test the quality of aspirin. Everyone seemed to enjoy working in a wet laboratory to make a molecule via a chemical synthesis and then testing their success with a colorimetric test.