Monitoring a reaction with thin layer chromatography lab report

Thin Layer Chromatography (TLC) Virtual Lab (20 Points) Part 1 Thin layer chromatography (TLC) is a simple and relatively fast analytical tool that is used to determine the number or identity of compounds in a mixture. It can also measure the extent of a reaction or measure the relative polarity of a molecule. A TLC plate is a sheet of glass that is coated with a thin layer of adsorbent such as silica (or occasionally alumina). A small amount of the mixture to be analyzed is placed or spotted near the bottom of this plate. When monitoring reactions, it is common to place the starting materials on one side of the plate (or in the left lane) and the reaction mixture in the right lane. The TLC plate is then placed in a shallow pool of a solvent (20% ethyl acetate/hexanes in part 2) so that only the very bottom of the plate is in the liquid. This solvent, or the eluent, is the mobile phase, and it slowly rises up the TLC plate by capillary action. As the solvent moves past the spot that was applied, it carries the spotted mixture up the plate where a competition occurs between the solvent carrying the mixture and the silica on the plate. Since the silica adsorbent is polar, polar molecules in the mixture will rise very little up the plate, but nonpolar molecules will have little attraction to the silica and will consequently rise to the top. Molecules of intermediate polarity will stop somewhere in between these two extremes. When the solvent has reached the top of the plate, the plate is removed from the solvent, dried, and then the separated components of the mixture are visualized by exposure to a UV lamp. The positions of each spot on the TLC plate are identified and recorded by assigning Rf values from 0.0 to 1.0, where a 0.0 indicates the spot is at the bottom of the plate and a 1.0 indicates the spot is at the top. In this part of the experiment you will complete the NC State Virtual Lab 1: Thin Layer Chromatography (TLC). https://go.ncsu.edu/vrlab-tlc You can also watch the videos on YouTube https://go.ncsu.edu/vrlab-tlc-captions You can add subtitles and speed up or slow down YouTube videos by clicking on the settings gear on the bottom right side of the video. Change the playback speed as desired. 1. Which of the compounds listed in the video would best be described as non-polar? (1 pt) 2. Which of the compounds listed in the video would best be described as polar? (1 pt) 3. Explain how TLC separates compounds? (2 points) 4. List the compounds that were found in spinach juice and their Rf values? (2 points) 5. Which compound has a higher Rf value beta-carotene or chlorophyll A? Explain your answer by discussing the molecules functional groups and polarity. (1 point) 5. How would the Rf values for the spinach extract change if the solvent in the developing chamber was more polar? (1 point) TLC Part 2 In this assignment, you will be guided through the steps of a simple esterification reaction as a demonstration of how to use thin layer chromatography as a tool to monitor a reaction until it reaches completion. This assignment will also serve as a tutorial to teach you how to utilize the various parts of the Beyond Labz organic simulation that will be used in later assignments. Reaction Intro: The aromas of many fruits and flowers are due to esters. The ester that will be synthesized in this virtual experiment, 3-methylbutyl phenylacetate, is naturally occurring in peppermint oil. It does not smell like peppermint but it has a sweet, pleasant odor. Esters can be formed by combining a carboxylic acid and an alcohol in the presence of a strong acid catalyst, such as sulfuric acid. In this virtual lab, 2-phenyl acetic acid and 3-methyl-1-butanol will react to form 3-methylbutyl phenylacetate. The overall reaction scheme is shown below. This experiment is meant to introduce you to Thin Layer Chromatography, the Beyond Labz platform, and provide you with an example of how to set up your laboratory notebook. Purpose: The purpose of this experiment is to synthesize 3-methylbutyl phenylacetate by combining 2-phenylacetic acid and 3-methyl-1-butanol in diethyl ether solvent and using concentrated sulfuric acid as a catalyst. The reaction will be heated under reflux and the progress of the reaction will be monitored using thin-layer chromatography (TLC). Once the TLC shows that the reaction is complete, the reaction will be quenched by adding aqueous base NaOH, and the product will be separated from the reaction mixture using liquid-liquid extraction.