October 15, 2010
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs
There are two approaches to deciding which scenario best fits the NMR data in the puzzle. A structure elucidator can provide evidence that one scenario is more probable than an other and/or eliminate one scenario on the grounds of insufficient/contradictory data to support it.
For the following 1H NMR spectrum, if the integral of the doublet at 7.42 ppm equates to 1 H atom from a single structure, then the 1H signals at 7.58-7.59 ppm integrating to 2.57 (and assuming all signals are accounted for) relate to overlapping signals (probably a doublet overlapping with a singlet) from a mixture of compounds at varying concentrations.
Another approach, as Adolfo has nicely provided, the magnitude of the strong coupling demonstrated by the signals at 7.58-7.59 ppm indicates a nearby partner on the left side circa 7.70 ppm. Since this appears not to be the case, then by process of elimination, the signals at 7.58-7.59 ppm relate to two overlapping multiplets.
