4-Phenylphenol Errors
I’d first like to say that while errors did occur during your TLC you did a good job getting visible results on your TLC plate, as sometimes it can be hard to get a sample to show up clearly on the plate. But not knowing which compound is which is a huge problem that will lead to incomplete conclusions and the need to redo your TLC. However, due to the knowledge we have of the compound on the plate we can determine which compounds are which. The two compounds you used are very similar in structure with one very important difference of the hydroxyl group on 4-phenylphenol that isn’t present in biphenyl. This hydroxyl group makes 4-phenylphenol more polar because of the possibility of hydrogen bonds between the compound and the silica on the
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The proper way to calculate Rf values is the distance your compound traveled divided by the distance your solvent traveled. In other words, you need to measure how far away from your baseline each compound is. You can choose which part of the spot you would like to measure to, either bottom, middle, or top, but once you choose you need to keep that consistent throughout all TLC plates you use for the same reaction. Once you’ve determined how far each compound has traveled you need to determine how far the solvent traveled. The best way to do this is to have a solvent front line close to the top of the TLC plate. From the picture of your TLC plate, I see that you had one; you should make sure all your solvent fronts are the same distance away from the baseline even if one TLC plate is shorter or longer than another. This will also make your calculations easier because your “distance solvent traveled” will be the same for all TLC plates. Once all Rf values are calculated you should see an upward trend the closer to the solvent front you get and a downward trend the closer you get to the baseline. Also, as a precaution, you should always circle the spots made on your TLC plate so you can always see how far they traveled and how intense they were. This will help when all your compounds are colorless and UV lights or an Iodine chamber is needed to view the
The proper way to calculate Rf values is the distance your compound traveled divided by the distance your solvent traveled. In other words, you need to measure how far away from your baseline each compound is. You can choose which part of the spot you would like to measure to, either bottom, middle, or top, but once you choose you need to keep that consistent throughout all TLC plates you use for the same reaction. Once you’ve determined how far each compound has traveled you need to determine how far the solvent traveled. The best way to do this is to have a solvent front line close to the top of the TLC plate. From the picture of your TLC plate, I see that you had one; you should make sure all your solvent fronts are the same distance away from the baseline even if one TLC plate is shorter or longer than another. This will also make your calculations easier because your “distance solvent traveled” will be the same for all TLC plates. Once all Rf values are calculated you should see an upward trend the closer to the solvent front you get and a downward trend the closer you get to the baseline. Also, as a precaution, you should always circle the spots made on your TLC plate so you can always see how far they traveled and how intense they were. This will help when all your compounds are colorless and UV lights or an Iodine chamber is needed to view the