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88 |
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Answers:
Doublets of the methyl protons in
(CH3)2CHOCH(CH3)2
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| bei n0 = 60 MHz
(see page 81), J = 6.1 Hz
(» 0.1 ppm) |
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bei n0 = 100 MHz,
J = 6.1 Hz
(= 0.061 ppm) |
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In other words:
If spectra are recorded at higher fields and - respectively -
frequencies while using the d scale,
then the spacing of the multiplet lines becomes tighter, while the
spacing of the signals remains constant.
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This effect is one of the reasons why spectra are recorded at increasingly
higher frequencies (Currently up to 900 MHz) - if there is a high
degree of coupling, multiplets may start to overlap if the spectra are
recorded at low fields (= frequencies). At higher fields the difference
between chemical shift and spin-spin coupling effects increases, and
the resolution of the spectra improves.
Now continue to page 85!
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