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Answers:

Doublets of the methyl protons in (CH3)2CHOCH(CH3)2
 
bei n0 = 60 MHz (see page 81), J = 6.1 Hz ( 0.1 ppm) bei n0 = 100 MHz, J = 6.1 Hz (= 0.061 ppm)
Spectrum 1 Spectrum 2


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.


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!