lab 7 - Yichen (Emily) Li 7/17/11 Experiment 7: Thin Layer...

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Yichen (Emily) Li 7/17/11 Experiment 7: Thin Layer Chromatography Discussion To narrow down the choice of TLC solvents used in Part II, my group observed the effectiveness of each solvent on the TLC plate. The four solvents we used were 100% ethyl acetate, 92:8 ethyl acetate: acetic acid, 60:40 hexane: ethyl acetate, and 10:10:1 toluene: ethyl acetate: acetic acid. According to our data, thin layer chromatography extracted the solute from 92:8 ethyl acetate: acetic acid, and 10:10:1 toluene: ethyl acetate : acetic acid. However, two of the solutes (2-acetamidophenol and caffeine) were inseparable in the 60:40 hexane: ethyl acetate solvent and one of the solute (caffeine) from the 100% ethyl acetate solvent was inseparable. We were able to detect this because the spots did not travel towards the solvent front. In addition, looking at their individual R f values (each less than 0.10) proves that the spots did not separate. Thus, we eliminated these two solvent systems as our potential choices. We observed that after performing thin layer chromatography on aspirin, acetaminophen, ibuprofen and caffeine, 1010:1 toluene: ethyl acetate: acetic acid separated the solutes really well because each solute is distinct on the TLC plate (very distant from each other). Overall, we picked 92:8 ethyl acetate: acetic acid and 10:10:1 toluene: ethyl acetate: acetic acid as our two solvent systems because the spots’ separation distance were greater than the other two solvents’. We identified out unknown B, which had a white and flaky appearance, by performing
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This note was uploaded on 09/29/2011 for the course CHEMISTRY 3AL taught by Professor Pedersen during the Spring '10 term at University of California, Berkeley.

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lab 7 - Yichen (Emily) Li 7/17/11 Experiment 7: Thin Layer...

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