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6. Solving simple structural problems by 1H-NMR
spectroscopy
1H-NMR spectroscopy has become a standard method in many
chemistry labs. A wide range of structural questions can be answered by
its application, since there are clear-cut relationships between the data
contained in 1H-NMR spectraand the arrangement of protons in
the molecules under investigation:
| Information contained in spectrum |
Proton arrangement |
covered on page |
| Number of resonance lines |
Number of groups of equivalent protons |
8 ff. |
| Position of resonance signals |
Type of groups of protons |
40 ff. |
| Relative intensities of the resonance signals |
Number of protons causing the signal |
53 ff. |
| Fine structure of the resonance signals |
Positioning of the proton groups with respect to each other |
72 ff. |
In many cases this knowledge enables us to
- predict spectra of molecules based on their
stereo formula
- propose a structure for an unknown molecule based on its spectra
- decide between several possible structures for a molecule based on
its spectra, or at least to limit the range of possibilities.
In the following we will address problems of the second and third type. If
one of your answers should differ from our solution, then please go back
and have another look at the exact question (Remember, this is our server,
and if we say so, then we are right).
If you should have trouble interpreting the various bits of information
carried in the spectra, then go back and have another look at the various
parts of this tutorial that cover the topic in question. (The links to the
different sections are given above)
Now take a deep breath and move to the first problem!
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