Thin Layer Chromatography Lab Report

Introduction: In this experiment, the identity and absolute configuration of an unknown chiral secondary alcohol will be determined using NMR and CEC. By using the given NMR data, the identity of the alcohol an be determined. In order to identify the stereochemistry of the alcohol, it will have to undergo an esterification reaction in which propionic anhydride, two enantiomers of HBTM(each used in different reactions), and triethylamine are used. Thin layer chromatography will be run at a specified time in the reaction, and the results will be examined both quantitatively(via ImageJ) and qualitatively to which reaction reacted more quickly. With this information, the stereochemistry of the alcohol can be deduced.

Theory: The competing enantioselective

It requires each enantiomer of the chiral acyl-transfer catalyst called homobenzotetramisole (R-HBTM and S-HBTM) and thin-layer chromatography (TLC). Identifying which HBTM enantiomer led to a faster reaction with the unknown chiral alcohol, and the use of a mnemonic allows for the identification of the configuration of the alcohol. In order to identify which HBTM enantiomer led to a faster reaction, a run TLC plate will be photographed (with a smartphone or any other photo-taking device) and a quantitative analysis will be performed using a program called ImageJ. In order to determine the molecular structure of the unknown alcohol that is received in lab, H NMR spectroscopy will be used. The rate of an enantioselective reaction for a matched alcohol and catalyst is faster than that of a

Therefore, the alcohol will prefer to react from the bottom face of the catalyst. Depending on which enantiomer of the alcohol is used, the reaction can occur quickly, or slowly. If the S-alcohol is used, the OH group will be positioned closer to the carbonyl, allowing for a quicker reaction. This would be a matched pair. If the R-alcohol is used, the OH group will positioned further from the carbonyl, leading to the reaction requiring more time. Furthermore, as the OH group approaches the carbonyl, the methyl group that neighbors the OH group will sterically interact with the phenyl group, repelling the alcohol from the carbonyl. This would be a mismatched pair. On the other hand, if the catalyst that was used is S-HBTM, then the phenyl group will be positioned down(as shown in the below image). Therefore, the alcohol will prefer to react from the top face. If the S-HBTM is reacted with the R-alcohol, the OH group will be positioned close to the carbonyl group, allowing it to react faster. This would be a matched pair. If, instead, the S alcohol is used, the OH group would be positioned further away from the carbonyl, leading to a slower reaction. This would be a mismatched