March 1, 2012
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs
For this puzzle, the objective is to extract structural information from the NMR data. However, the underlying message is to check all possible atomic combinations so that no plausible fragment gets overlooked.
For an unknown compound, an expanded region of the 1H-13C HSQC-DEPT spectrum below shows two 1H multiplets and two negatively-phased correlations (blue). The 1H integrals show the correlations to be 1 Hydrogen atom each. The 1H multiplets are both aligned with the 13C shift at 107.9 ppm. Is the 13C shift at 107.9 ppm due to a CH, CH2 or CH3 group? Is there another fragment that should be considered?