What does DEPT NMR show?
Distortionless Enhancement by Polarization Transfer NMR ( DEPT NMR) and Attached Proton Test NMR (APT NMR) are 13C NMR experiments that reveal the number of protons that are attached to individual 13C carbon atoms in a molecule.
What is polarization transfer in NMR?
Polarization transfer in NMR spectroscopy is a process by which the magnetization of one nuclear species, S (usually protons) is transferred to another nuclear species, I, through a scalar coupling, JIS” This results in a signal enhancement of the I nuclei by Yg7Yr’ where y is the gyromagnetic ratio.
WHAT IS A DEPT 135 spectrum?
The DEPT-135 gives signals of all protonated carbons, but CH and CH3 signals are positive, while CH2 peaks are negative. The signals of quaternary carbons are absent in all the DEPT spectra. By combining the DEPT-45, DEPT-90 and DEPT-135 spectra, it is possible to determine multiplicity of each carbon signal.
What are the different dept techniques discuss their application?
The DEPT sequence is a clever combination of the coherence transfer techniques of the Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) experiment and the spin-echo protocol of the attached proton test (APT).
How does a DEPT experiment work?
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.
Which compound generates positive peaks for the carbonyl in both its Dept 90 and Dept 135 spectra?
Methine carbons
Methine carbons (CH) appear as positive peaks in both DEPT 90 and DEPT 135 spectra. Methylene carbons (CH2) don’t appear in DEPT 90 and appear as negative peaks in DEPT 135 spectra. Methyl carbons (CH3) don’t appear in DEPT 90 and appear as positive peaks in DEPT 135 spectra.
How does Hsqc work?
HSQC works by transferring magnetization from the I nucleus (usually the proton) to the S nucleus (usually the heteroatom) using the INEPT pulse sequence; this first step is done because the proton has a greater equilibrium magnetization and thus this step creates a stronger signal.
What is DEPT technique?
Distortionless enhancement by polarization transfer (DEPT) is an NMR method used for determining the presence of primary, secondary and tertiary carbon atoms.
How many nuclear spin states are possible for the 1H nucleus?
two possible
1H nuclei (protons) exhibit two possible magnetic spin orientations.