March 1, 2011
The intensity of a correlation in relation to other correlations on a 2D NMR spectrum can be just as important in a structure elucidation as assessing the position and phase of a correlation. The example below presents one such case.
From the 1H-13C HSQC in the previous post, the correlations differ significantly in intensity. The weaker correlations can be attributed to long-range couplings, more specifically, 2J coupling responses. In addition to the 1H integrals, the carbons at 121 and 134 ppm are probably CH’s (4 CH’s in total) and probably not CH2’s. Two potential fragments are shown below and here.