Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Start Practicing

Worksheet: Carbon NMR Spectra

Q1:

Carbon NMR is harder to do than proton NMR because:

  • AThe mechanism of interaction of the isotopes of carbon (number 13) with a magnetic field is dependent on how many hydrogens are attached to it.
  • BIt has a higher atomic mass which makes it slower to move and relax on the NMR time scale.
  • CThe gyromagnetic ratio (NMR sensitivity factor) is over 100 times less for carbon-13 than for hydrogen-1.
  • DThe actual atoms of carbon observed (the isotope we can detect) is of lower relative abundance than for hydrogen.

Q2:

How does the range of chemical shifts in carbon-13 NMR differ from that in proton NMR?

  • ACarbon-13 and proton NMR signals span similar ranges of chemical shifts, but the positions of carbon-13 signals are more sensitive to the effects of solvation and hydrogen bonding.
  • BCarbon-13 and proton NMR signals span similar ranges of chemical shifts, but changes in chemical shift are harder to detect in carbon-13 NMR due to the lower signal intensity.
  • CCarbon-13 NMR signals span a much narrower range of chemical shifts and are less sensitive to the chemical environment.
  • DCarbon-13 NMR signals span a much wider range of chemical shifts and are more sensitive to the chemical environment.
  • ECarbon-13 NMR signals span a much wider range of chemical shifts, but changes in chemical shift are harder to detect due to the lower signal intensity.