Sucrose 2D NMR Spectra
The sugar sucrose can be used to illustrate homonuclear 2D NMR experiment: the TOCSY.
Sucrose (“table sugar”) is a disaccharide derived from glucose and fructose.
The interesting element from an NMR spectroscopy viewpoint is that the two monomer units are completely separate spin systems and this can be visualised in the TOCSY spectrum.
The HH COSY shows the coupling network within the molecule.
The HH TOCSY spectrum shows correlations that belong together in contiguous spin systems: in the sucrose example, this means that the protons in the respective glucose and fructose units can be assigned.
In the HMQC spectrum the one-bond direct HC couplings can be viewed as cross-peaks between the proton and carbon projections.