April 15, 2009
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs
Chemical shift information offers a clue into an atom’s hybridization state. For example, carbon atoms with a carbon chemical shift greater than 90 ppm are typically considered as sp2 carbons. If 4 sp2 carbons are present, one can infer 2 alkene pairs. Five sp2 carbons and an available oxygen and nitrogen atom suggest the possibility of a pyridinone fragment.
The example below shows a 5 sp2 carbons and 2 sp3 carbons, coloured pink and blue, respectively. The chemical shift at 167 ppm for the quaternary carbon suggests the presence of an amide group.
Using the information described above, a set of 6 possible candidate structures can be pieced together.
I need your expertise for explaining 1H nmr of my compound..my compound is a pyrdinone compound with imidazole substiutent..surprisingly, i find all the imidazole protons as singlets..why is it so? Please explain this unsusual pattern
I received your comment on my blog. FID processing, data acquisition, temperature, concentration, etc. can influence the displayed coupling pattern. Without FID data to examine, I cannot be certain which scenerio is applicable.