Two-Dimensional Heteronuclear Relayed Coherence Transfer RCT Spectroscopy

5 TWO-DIMENSIONAL HETERONUCLEAR RELAYED COHERENCE TRANSFER (RCT) SPECTROSCOPY 

The most informative source for deducing connectivities in organic molecules are proton and carbon coupling constants. There are three main methods which can be used for determining proton and carbon connectivities (A) Homonuclear proton 2D-shift correlation spectroscopy combined with 

Haasnoat, F.J.M. Van de Ven, and C.W. Hilbers, COCONOSY combination of 2D correlated and 2D nuclear Overhauser enhancement spectroscopy in a single experiment, J. Magn. Resonance 56, 343 (1984). 

This brings us to the question How much material is required in order to record conventional heteronuclear 2D-shift correlated spectra and relayed coherence transfer spectra As mentioned in an earlier chapter, the sensitivity increases with increasing proton resonance frequency of the NMR spectrometer. On a 300-MHz instrument, one requires a minimum solution concentration of 0.02M (i.e., 0.05 mmol material or 20 mg of a compound of molecular weight 400) in order to record a 2D shift correlation 

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