Functional Group Chemical Shifts in NMR Spectroscopy for Organic Chemistry 

This is a tutorial screencast on the location of functional groups in proton and carbon nuclear magnetic resonance spectroscopy or NMR. Why is NMR useful? Well, depending on the functional group present in the molecule, the hydrogen atom or carbon atom will be observed in a different region of the spectrum. This is helpful because if we are given an unknown compound and asked to determine its structure, we can look at the different regions to confirm the presence of a functional group or if it is absent to rule it out. The location of a resonance or peak on the x-axis of the spectrum is called the chemical shift and is reported in parts-per-million (ppm), which is abbreviated with the Greek letter delta. The x-axis for both 1H and 13C spectra have two general regions called "upfield" and "downfield." These are older terms that relate the peak location to the magnetic field strength and they are helpful in conveying information when we talk about the relative location between peaks. Notice the 1H NMR axis has a range between 0 and 12 ppm while the 13C is between 0 and 220. The region toward 0 in both cases is called upfield and the toward the higher chemical shift is called downfield. In both 1H and 13C NMR the functional groups are observed in nearly the same order from 0 ppm but just spread out amongst either 12 or 220 ppm.