Final answer:
The main difference between C-NMR and H-NMR is the amount of material required, with C-NMR typically needing a larger quantity of sample due to lower natural abundance and sensitivity of carbon-13 compared to protons.
Step-by-step explanation:
The main difference between preparing a sample for C-NMR (Carbon-13 Nuclear Magnetic Resonance) and H-NMR (Proton Nuclear Magnetic Resonance) is the amount of material required. In H-NMR, the sensitivity is generally higher because protons are more abundant and they also have a higher gyromagnetic ratio compared to carbon-13 nuclei. This means that for H-NMR, a smaller amount of sample is typically needed to achieve a good signal. Conversely, for C-NMR, a larger quantity of sample is usually necessary because carbon-13 is less naturally abundant (only about 1.1% of carbon atoms are carbon-13) and has a lower sensitivity. Advanced spectrometers like those mentioned in the provided experimental sections improve the efficiency of NMR spectroscopy, but the fundamental difference in sensitivity and natural abundance still necessitates more material for C-NMR analysis.