1. Carbon-13 12C is not NMR-active (no magnetic spin (I = 0))
13C has a magnetic spin (I = 1/2 , odd mass)
13C signals are 6000 times weaker than 1H because:
Natural abundance of 13C is small (1.08% )
Magnetic moment of 13C is small
The gyromagnetic constant of 13C is one-fourth of that of 1H
The chemical shift range is larger than for protons
ppm
The number of different signals indicates the number of different kinds of carbon
PULSED FT-NMR is required
13C g = 6.72
1H g = 26.75

3. Coupling Constants 13C - 13C coupling NO! not probable
However, 13C does couple to hydrogen atoms (I = 1/2)
13C – 1H
coupling
YES!
very common

4. Coupling to attached Protons

5. Decoupling the Proton Spins
Proton-Decoupled Spectra
Off-resonance decoupling

6. Ethylphenylacetate

7. Some Instruments Show The Multiplicities of
The Peaks on The Decoupled Spectra
s = singlet t = triplet
d = doublet q = quartet
CODE :

8. Hydrogen and Carbon Chemical Shifts

9. Correlation chart for 13C Chemical Shifts (ppm)

10. Approximate Chemical Shift Ranges (ppm) for Selected Types of Carbon.

11. 1-Propanol

12. 2,2-Dimethylbutane

13. Bromocyclohexane

14. Cyclohexanol

15. Cyclohexene

16. Cyclohexanone

17. Toluene

18. 1,2-Dichlorobenzene a b c

19. 1,3-Dichlorobenzene

20. Estimation of Carbon Chemical shifts in Substituted Benzene