|Chapter 13: Spectroscopy|
DEPT C-NMR Spectra
As stated previously, normal 13C spectra are broadband decoupled. With the development of more modern spectroscopic methods it has become possible to use a programed sequences of radio frequency pulses to determine other structural features.
One of these techniques is known as DEPT (distortionless enhancement of polarisation transfer) which can be used to give similar information to an off-resonance decoupled spectra i.e. the number of attached H.
In a DEPT experiment, a sequence of pulses with various delay times are used to create the DEPT spectra where -CH3 and CH peaks appear as normal and -CH2- peaks appear inverted. Quaternary C are not usually seen. This way the number of H attached to C can usually be deduced. An example of a DEPT is shown below for 2-butanol (notice how the peak for the -CH2- points down) with the corresponding broadband decoupled spectra.
|© Dr. Ian Hunt, Department of Chemistry|