Question

Compare proton NMR and C-13 NMR in terms of their ability to show how many hydrogen or carbon atoms are associated with a given signal.

Answer 1

¹H-NMR can give you lot of informations because of the multiplicity of the signals.

Can't observe multiplicity of the signals in In ¹³C-NMR (not always true).

Reason: The low natural isotopic abundance of ¹³C which is 1,1%. It means that because of the low isotopic abundance of ¹³C so it will be very difficult to find two ¹³C linked together inside the carbon backbone of the molecule.

it's easy to notice multiplets because of the higher isotopic abundance of ¹H which is more than 99%, so coupling can occur in ¹H-NMR spectra.

• Another difference is related to the chemical shift range of absorption for the both techniques.¹H-NMR range is from 1 to 10 ppm instead ¹³C-NMR goes from 10 to 200 ppm.

¹H NMR a useful spectrum can be obtained very quickly (5 minutes) with a few milligrams of material, however with ¹³C NMR normally the minimum scan time would be longer (~20-30 minutes) for more concentrated sample.

¹³C NMR detects only the ¹³C isotope of carbon and with the help of Distortionless enhancement by polarization transfer spectra, we can determine the presence of primary, secondary and tertiary carbon atoms.

Solvent peak is not observed in proton NMR and Area under the peak is considered.TMS peak is singlet.Effect of substituent on adjacent carbon atom can varies chemical shift.

Solvent peak is observed. in ¹³C NMR.TMS peak is quartet. Area under the peak is not considered. Effect of substitute on adjacent carbon atom cannot varies chemical shift.