Something know about carbon 13 nmr comperision with c13 nmr and h1 nmr

1. Seminar Topic – Chemical shift of C¹³ NMR
GUIDED BY PRESENTED BY
Dr. Mohd.Talha Naresh Patel
MSc. 3rd semester
(Chemistry)

2. Introduction -
 It is also known as CMR.
 The ¹³C NMR is generated NMR is generated in the same
fundamental was as proton NMR spectrum. It also provides
direct information of Carbon & Hydrogen.
 There are three isotopes of C: 12, 13 & 14. ¹²C & ¹⁴C are
NMR inactive because their (i) values are zero and even.
Only ¹³C is NMR active.

3. Abundance & some property
¹H – NMR ¹³C - NMR
Abundance 98% 1.1%
Information about hydrogen in different
chemical environment
Carbons in different
chemical environment
Gyromagnetic ratio 267
More sensitive in CMR
67
¼ Of H ( less sensitive)
Coupling Between Adjacent ¹H
(Seen)
¹³C - ¹H & ¹³C - C¹³
(Possible)
Time 3mg – 1min. 30mg – 40-50 min
CH⁴ Singlet Pentet

4. Chemical Shift Scale & Reference
In ¹H NMR max 15 ppm & in ¹³C NMR 240 (δ)ppm
relative to TMS. Thus fewer overlap in ¹³C NMR
Why used TMS as a Reference
1. Chemically inert, Miscible with overall solvent
2. 12 magnetically equivalent proton (1 signal)
3. Proton are highly shielded give a strong peak in less quantity
4. Less En. & Volatile and easily removed.

5. TMS – (δ)Scale
13C-NMR:
Different carbons appear at
different frequencies – Now
you know how many different
types of Carbons you have!
De-shielded
(Down field)
Shielded
(Up field)
B
A
Which has more
hydrogen
Which has less
hydrogen

6. Chemical Shift in ¹³C - NMR
ppm (δ) Value Conditions
 C → (Sp³)
 C → X (Sp³)
 C → (Sp) C≡C, C≡N
 C → (Sp²) C=C, Ar.
 -CHO, -CO, CO2R, CONH2
 10-40 ppm
 40-80 ppm
 80-115 ppm
 100-150 ppm
 150-220 ppm

7. Approximate Value of Chemical shift for ¹³C- NMR

8. Factor affecting the ¹³C Chemical shift
1). Deshielding effect of electronegative moiety

9. 2). Effect of Hybridization
Hybridization
 Sp³ - S=25%
 Sp² - S=33%
 Sp - S=50%
ppm value
 2 to 55 ppm
 110 to 170 ppm
 65 to 90 ppm
*(anisotropic effect)

10. 3). Effect of Substitute
n- Pentane -CH3 -CH2 -CH2 -CH2 -CH3
(δ) value 13.7 22.6 34.5 22.6 13.7
Example. Cl substitution
1- Chloro
Pentane
-CH3 -CH2 -CH2 -CH2 CH2Cl
(δ) value 13.6 22.1 29.2 32.7 44.3

11. Thank you