Introduction In a two-week laboratory experiment my group and I used the techniques of acid-base extraction and Thin Layer Chromatography (TLC) to extract the three active compounds in Excedrin- aspirin, acetaminophen, and caffeine- and confirm the identity of our extracted crystals. The purpose of this experiment is to introduce organic chemistry lab students to the laboratory techniques of acid-base extraction and TLC. This lab also offers the opportunity to apply the previously theoretical classroom concepts of acidity, solubility, and polarity in order to utilize acid-base extraction and TLC. The aim of this experiment is to take an Excedrin tablet and use the varying acidities of the 3 active components to separate them using acid-base …show more content…
Solubility matters since organic compounds tend to not be soluble in aqueous solvents, but ionic salts do easily dissolve in water. And acidity matters since we can adjust the base strength to only react with one component of Excedrin at a time, allowing for the components to be isolated. By adding a 1M solution of a basic salt, like K2HPO4 or KOH, to organic compounds, we could convert the organic components of Excedrin into ionic salt that will dissolve in aqueous solvents. Next, by adding a strong acid, like HCl, the Excedrin component is protonated causing a decrease in solubility leading to the component precipitating out of the solution and crystallizing. Acid-base extraction offers a method to separate the active components of Excedrin based on acidity and what bases they will react with. Acid-base extraction also leads to recrystallization which due to the components forming lattices usually results in pure crystals that can be analyzed with TLC. Acid-base extraction is important because it offers a different way to extract the components of a mixture that does not involving boiling the solution. The lack of temperature dependence is useful for molecules whose solubility in water do not vary significantly with temperature. This extraction method is relevant to separate the components of Excedrin providing pure products without needing to use the stock-room version of the compound. Acid-base extraction is also relevant and important because it allows a student to utilize a variety of chemistry concepts including solubility of organic compounds, solubility of salts, acidification, and