The last part of the experiment involved analyzing

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The last part of the experiment involved analyzing the final purified product using a TLC system. TLCs allow for the comparison of compounds based on their polarity, with the most polar substances migrating the least and the least polar, or most non-polar compounds migrating the furthest. The TLC results displayed above were borrowed from Kitty Chan and Andrew
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Hanna, and indicate a near perfect purification. As seen, the relative migration of the sublimed recrystallized caffeine sample and the reference sample were almost identical, differing by less than 10% in Rf values in each solvent system. Because both samples migrated almost identically, we can infer that their chemical compositions were also almost identical, indicative of a successful purification. In our case, the TLCs in both solvent systems did not display any spots at all. This can most likely be attributed to an unknown problem with our solvent systems. In some cases, if the solvent system is too high initially, where it is above the spots on the TLC when it is inserted, the compounds from the spots can dissolve in the solvent instead of migrating up the plate. In terms of our melting point, which was determined from our sample to be between 238 and 244ºC, this is indicative a slightly impure final product. However, this was to be expected as our crude caffeine sample was used for boiling determination due to a lack of purified caffeine yield. References Pauli, G. F., Chen, S. N., Simmler, C., Lankin, D. C., Gödecke, T., Jaki, B. U., … Napolitano, J. G. (2014). Importance of purity evaluation and the potential of quantitative 1H NMR as a purity assay. Journal of Medicinal Chemistry . (Pauli et al., 2014) Appendices
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