NMR spectra — especially 2D spectra — contain a wealth of information. It is important, therefore, to be certain of the relative value of each single piece of information. There are “soft” clues or hints that can only be evaluated through experience and a knowledge of analogous findings, i.e., on the basic of empirical evidence. A typical example is the evaluation of the chemical shifts (δ) of an atom by taking into account the nature of its neighboring atoms. Such hints should, whenever possible, be verified by experimental results. Information from characteristic S ranges are more reliable. For instance, it is clear that a 13C signal with δ = 210 corresponds to a carbonyl carbon and that this carbon cannot be a member of a carboxyl function. Many 1H, 1H and 13C, 1H coupling constants belong to the same category.
KeywordsCross Peak Cosy Spectrum Signal Splitting Signal Assignment Methine Carbon
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