1. Start nice and simply. How many peaks would you expect in the C-13 and low resolution (i. e., no splitting) H-1 NMR for the 3 isomers of pentane?

2. Here are the high-resolution spectra for two of the isomers of pentane. Assign which is which and also assign the signals to the particular hydrogen atoms:

3. Now let’s up the ante. Spectra A to E (in spectra sheet) are the carbon spectra for the 5 isomers of hexane. Assign each.

4. How many peaks would be expected in the low resolution spectra of each of these isomers of hexane, and how many H would be represented by each?

5. Spectra F to K (no I) are the high resolution spectra of the isomers of hexane. Assign which is which and also assign the signals to the particular hydrogen atoms.

6. Spectra L to P (no O) are the high resolution spectra of propan-1-ol, propan-2-ol, propionic acid and propionitrile (CH₃CH₂CN). Assign each and explain why by detailing which signals correspond to which protons. As these are real spectra, the signals can appear to be doubled up. I have labelled a couple of cases where this could be ambiguous (but I have not labelled all of them!)

7. A worksheet would not be complete without considering some acid derivatives. There are 7 carbon-13 spectra labelled C1 to C7 and 7 H- spectra labelled H1 to H7. Do note that there is a C-13 and H-1 spectrum for each compound BUT the numbers do not match (e. g., C1 and H1 are not of the same compound.) All of the 7 compounds are isomers of C₄H₈O₂. There are two acids, 3 esters, one lovely compound that has a ketone group and a secondary alcohol and then a mystery compound with the name of methoxyacetone. Your task – match the C-13 and H-1 spectra and try to identify the compound in each case. [NOTE: I have put enough integrations (numbers of H) for you to know the rest]

PROTON SPECTRA:

CARBON SPECTRA:

8. Alkenes introduce another level of fun into NMR assignments. Consider the spectra shown in the Question 8 set of chloroethene.

a) In the top spectrum, there are 3 peaks for one hydrogen each. Explain why each hydrogen is unique rather than at least 2 being equivalent.

b) The second spectrum is a high res spectrum, and the interesting bits are pulled out to the left and the right. Explain the splitting patterns observed.