Combined spectroscopy problems - CU Boulder PDF

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Download Combined spectroscopy problems - CU Boulder PDF

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Combined spectroscopy problems From CU Boulder, http://www.orgchemboulder.com/Spectroscopy/Problems/index.shtml

“Spectroscopy Problems In each of these problems you are given the IR, NMR, and molecular formula. Using this information, your task is to determine the structure of the compound. The best approach for spectroscopy problems is the following steps: 1. Calculate the degree of unsaturation to limit the number of possible structures. Remember, each degree of unsaturation is a ring or pi bond (likely an alkene or carbonyl). An alkyne has two degrees of unsaturation (2 pi bonds), and an aromatic ring has four (3 pi bonds plus a ring.) Although there's no guarantee, if your structure has more than four degrees of unsaturation it's quite likely to have an aromatic ring. 2. Look at the IR absorption bands at wavenumbers above 1500 cm-1 to determine what functional groups are likely in the compound. Remember that these functional groups must be consistent with the degree of unsaturation. 3. Look at the NMR to determine the connectivity of the compound. If you can't figure out the entire structure at once, it helps to come up with fragments of the molecule that you can stick together into larger and larger groups until you have the entire structure. 4. Approach this as a puzzle - it can be fun!”

Problem 1

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Problem 9

Problem 12...