Thin Layer Chromatography Lab Report

The goal of this experiment was to use the technique of thin layer chromatography (TLC) to identify the active analgesic ingredient of Advil and monitor the transesterification of methyl salicylate from acetylsalicylic acid. The synthesized methyl salicylate was then purified using acid-base chemistry and analyzed using H NMR spectroscopy. Identification of a proper mobile phase to separate common analgesics used in over-the-counter pain relievers was essential in being able to determine the active ingredient in Advil. Therefore, in Procedure 1 TLC trials were ran for acetaminophen, aspirin, caffeine, and ibuprofen in different mobile phases composed of various proportions of ethyl acetate and hexane. The Rf values were recorded in Table 1.
Based on this data, a mobile phase composed of 80% ethyl acetate and 20% hexane was selected, for it provided a Rf value significantly greater than 0 for all analgesics and showed a decent amount of separation. This is vital in TLC because it is very difficult to differentiate chemicals unless separation is seen. …show more content…
This reaction was run in a reflux reaction vessel for heat is a crucial component to this equilibrium reaction, and the retention of as much methyl salicylate as possible is vital. As seen in Figure 2 and Table 3 at the start of the reaction, there was no methyl salicylate or salicylic acid (intermediate) in the solution. However, at the point of reflux salicylic acid appeared and 20 minutes later methyl salicylate began to form. At the 40 minute mark, the majority of the methyl salicylate was formed, and there was still a significant amount of intermediate left in the reaction solution. The amount of methyl salicylate did not change between 40 and 60 minutes, so the reaction was stopped and the solution was allowed to cool before extracting the methyl salicylate with acid-base