 |
73 |
|
Answers:
- If the magnetic fields of two protons can interact via
s- and p-
electrons in bonds connecting the two protons directly, or indirectly
over additional nuclei, then their energy levels in the external
magnetic field of the spectrometer will show additional splittings.
Because of that additional transitions with only small differences
in energy become possible.
- Since these interactions are mediated by bond electrons,
this phenomenon is referred to as through-bond spin-spin
coupling.
- In the most basic case, when only n equivalent protons X are coupling
to the proton A, the following relationship exists between the number
of coupling protons and the multiplicity MA of the signal
dA
- In this case the relative intensities of the lines in various
multiplets follow characteristic patterns:
| Multiplicity |
Relative intensities |
| 2 |
1 : 1 |
| 3 |
1 : 2 : 1 |
| 4 |
1 : 3 : 3 : 1 |
| 5 |
1 : 4 : 6 : 4 : 1 |
Do you need some more hints on these questions?
Check here!
Otherwise try to apply your knowledge in the next excercise.
Draw a schematic NMR spectrum of the molecule
R2CH-CH3!
Compare your solution to the correct answer on page 75!
|
|
|
|
|
