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!

You can use the buttons at the bottom of each page reveal part or all of the answer.

1. Problem 1
2. Problem 2
3. Problem 3
4. Problem 4
5. Problem 5
6. Problem 6
7. Problem 7
8. Problem 8
9. Problem 9
10. Problem 10
11. Problem 11
12. Problem 12
13. Problem 13
14. Problem 14
15. Problem 15
16. Problem 16
17. Problem 17
18. Problem 18
19. Problem 19
20. Problem 20

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