chem233_postlab10 - disproportionation redox reaction could...

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Post Lab 10 1. One major chemical reason for not obtaining 100% yield is that the reaction may not have gone to completion. This is possibility in every chemical experiment, but in this lab specifically, perhaps not enough time was given. We were supposed to let it sit for 15 minutes, but this may not have been long enough. Another possible chemical reason is that a self aldol reaction could have occurred rather than the proper aldehyde to ketone reaction. Some physical reasons include losing some product, and this is especially possible because we were forced to run the vacuum filtration multiple times due to the product slipping through the filter paper. All these reasons contributed to our 23.7% yield. 2. The major side reaction that could occur would be a self aldol reaction, as the aldehydes or ketones could react with themselves rather than reacting together. One way to tell if this occurred would be to plate it on a TLC plate, where differences can easily be seen. The Cannizzaro
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Unformatted text preview: disproportionation redox reaction could have also occurred, where the compounds could have been reduced to alcohols, and this could be seen by an IR spectra. 3. In this lab, we transformed p-anisalaldehyde into trans-p-anisalacetophenone and then collected the product through vacuum filtration and recrystallization. We had a few key errors, however, which caused our yield to only be 23.7%. One was that the vacuum filtration efficiently separate the product from the solution, as it went through the filter paper fairly easily, so we had to perform it multiple times. Despite this deficiency, I do believe we were successful, as the TLC plate and the matching melting points mean that our product was very pure, although not much was collected. 7. The coupling constant for peaks D and G are 15.6 Hz, which corresponds to the 11-19 Hz range that trans alkene products occur, so this is the evidence. The H beta is less shielded so it has a larger chemical shift and is farther upstream....
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