c nuclear magnetic resonance - chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.cnmr.pdf ·...
TRANSCRIPT
![Page 1: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/1.jpg)
13C Nuclear Magnetic Resonance
Inherent Difficulties
• Low abundance of 13C (1.1% vs, 99.9% for 1H) • Lower gyromagnetic ratio (1/4 that of 1H) - 13C: 67.28 vs. 1H 267.53 • Slow T1 relaxation times (10-100 sec vs. 0.1-1 sec for 1H) • 13C-1H coupling complicates spectrum; decreases peak intensity
ΔE
magnetic field (B0)
-1/2
+1/2
1,000,000 nuclei at 60 MHz
1,000,009 nuclei at 60 MHz
E
![Page 2: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/2.jpg)
13C Nuclear Magnetic Resonance
Chemical Shift
see also Pavia Table 6.1; Appendices 7 & 8
![Page 3: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/3.jpg)
13C Nuclear Magnetic Resonance
Chemical Shift
Factors the Influence Chemical Shift
1. hybridization 2. electronegativity of element bonded to carbon 3. anisotropy
OH O
**
*
**
δ 22.6 δ 139.0 δ 38.2
δ 62.3 δ 202.8
![Page 4: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/4.jpg)
13C Nuclear Magnetic Resonance
Differences Between 1H and 13C NMR
1. range of 13C chemical shifts is very large compared to 1H 2. 13C chemical shifts are more sensitive to small changes in chemical environment 3. Influence of electronegative atoms on chemical shift greater in 13C NMR than 1H NMR 4. Homonuclear (13C / 13C) splitting is not observed
See Pavia, Appendix 8 for calculation of 13C chemical shifts
CH3 CH2 CH2 CH2 CH2 CH2 OH
0.90
1.32
1.32
1.32
1.56
3.62
CH3 CH2 CH2 CH2 CH2 CH2 OH
14.2
22.8
32.0
25.8
32.8
61.9
1H shifts 13C shifts
![Page 5: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/5.jpg)
NMR Spectra of n-Butylbenzene
![Page 6: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/6.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Spin-Spin Splitting (1H-13C)
CH2 CH3 CH2
3J = 0-3 Hz
![Page 7: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/7.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Spin-Spin Splitting
1H coupled spectrum
1H decoupled spectrum
HOH H
HH
cholesterol
![Page 8: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/8.jpg)
13C Nuclear Magnetic Resonance
Proton Decoupled 13C NMR
![Page 9: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/9.jpg)
13C Nuclear Magnetic Resonance
Proton Decoupled 13C NMR 1H coupled spectrum
1H broadband decoupled spectrum
1H off resonance decoupled spectrum
CH3
CH3
![Page 10: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/10.jpg)
13C Nuclear Magnetic Resonance
Nuclear Overhauser Effect & Cross Polarization of Spin
300 MHz
Signal Enhancement: CH3 > CH2 > CH >> C
B0
1H
decoupler
B0
13C
crosspolarization
Boltzmandistribution
NupperNlower
= 1,000,0001,000,048
1,000,0001,000,096
=
NupperNlower
= 1,000,0001,000,048
1,000,0001,000,000
=Boltzmandistribution
11
=
![Page 11: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/11.jpg)
13C Nuclear Magnetic Resonance 13C Pulse Sequence
FID:
![Page 12: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/12.jpg)
13C Nuclear Magnetic Resonance
Relaxation Times (T1)
CH3 C CH2 CH CH3
CH3
CH3
CH3
9.3 s
68 s
13 s23 s
9.8 s
T1 : C > CH > CH2 > CH3
in general
tumbling
HOH H
HH
T1 = 37 s T1 = 20 sT1 = 1-2 s for CH, CH2, CH3T1 = 4-6 s for quaternary C
![Page 13: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/13.jpg)
13C Nuclear Magnetic Resonance
Molecular Symmetry
How Many Lines?
C-CH2-CH3CH3
CH3CH3
O H3C
H3C
CH3
OH
CH3H3C
A B C D
![Page 14: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/14.jpg)
13C Nuclear Magnetic Resonance
Integration
A
B
C
D
2 peaks
1
2
3
4
![Page 15: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/15.jpg)
13C Nuclear Magnetic Resonance
Distortionless Enhancement by Polarization Transfer (DEPT)
DEPT-45 DEPT-90 DEPT-135 C 0 0 0
CH + + +
CH2 + 0 -
CH3 + 0 +
![Page 16: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/16.jpg)
13C Nuclear Magnetic Resonance
Distortionless Enhancement by Polarization Transfer (DEPT)
CCHCH2CH3
DEPT-450+++
DEPT-900+00
DEPT-1350+-+
DEPT-135
DEPT-90
DEPT-45
13C NMR 1 2 46 78 9 935
CH3
OH
H3C CH3
menthol
3
5
12
4 6
7
89 9
![Page 17: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/17.jpg)
13C Nuclear Magnetic Resonance
DEPT-135 O
NH
CH3O H
OH
CH3O2C OH
OH
OH
O CH3
![Page 18: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/18.jpg)
13C Nuclear Magnetic Resonance
Alkanes
2-methylpentane
CH-CH2-CH2-CH3CH3
CH3a
b dc e
a
e b
c
a
d
R CH3
R2 CH2
CR4
15-55 ppm
30-40 ppm
8-30 ppm
chemical shifts
CHR3 20-60 ppm
![Page 19: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/19.jpg)
13C Nuclear Magnetic Resonance
Alkenes
cis-2-hexene
C C 110-150 ppm
chemical shifts
C CH
H3C CH2CH2CH3
H
ea
b
d
c
f
e b c
a
d 123.9 130.7
29.1 f
![Page 20: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/20.jpg)
13C Nuclear Magnetic Resonance
Alkenes
1-hexene
C C 110-150 ppm
chemical shifts
b
a
114.2
139.2
e abd cf
CH3-CH2-CH2-CH2-CH CH2
![Page 21: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/21.jpg)
13C Nuclear Magnetic Resonance
Alkenes
dihydropyran
C C 110-150 ppm
chemical shifts
b
a
100.7
144.3 O a
b
![Page 22: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/22.jpg)
13C Nuclear Magnetic Resonance
Alkenes
4-methyl-2-penten-1-one
C C 110-150 ppm
chemical shifts
b
a 154.8 124.3 H3C
H3C
O
CH3
a
b
![Page 23: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/23.jpg)
13C Nuclear Magnetic Resonance
Aromatics
nitrobenzene
C110-175 ppm
chemical shifts
b c
a
d
NO2ab
c
d
![Page 24: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/24.jpg)
13C Nuclear Magnetic Resonance
Aromatics
p-cymene
CH3
C110-175 ppm
chemical shifts
![Page 25: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/25.jpg)
13C Nuclear Magnetic Resonance
Aromatics
dichlorobenzenes
Cl
Cl
Cl
Cl
Cl
Cl
C110-175 ppm
chemical shifts
![Page 26: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/26.jpg)
13C Nuclear Magnetic Resonance
Alkynes
2-heptyne
b
a
65-90 ppm
chemical shifts
C≡C
C C CH3CH3CH2CH2CH2ab
79.4
75.3
![Page 27: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/27.jpg)
13C Nuclear Magnetic Resonance
Alkyl Halides
1-chloropentane
C I
25-65 ppm
35-80 ppm
-5-40 ppm
chemical shifts
C Br
C Cl
aCH3 CH2-CH2-CH2-CH2-Cl a
45.1
![Page 28: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/28.jpg)
13C Nuclear Magnetic Resonance
Alcohols, Ethers & Amines
2-hexanol 40-60 ppm
50-80 ppm
chemical shifts
C-OR
C-NR2
CH3CH2CH2CH2 CHCH3OH
aa
68.0
![Page 29: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/29.jpg)
13C Nuclear Magnetic Resonance
Alcohols, Ethers & Amines
1,3-dioxane 40-60 ppm
50-80 ppm
chemical shifts
C-OR
C-NR2
bc
O Oa
a
b
c
![Page 30: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/30.jpg)
13C Nuclear Magnetic Resonance
Alcohols, Ethers & Amines
N-methylisobutylamine 40-60 ppm
50-80 ppm
chemical shifts
C-OR
C-NR2
d
b c
NH
a b d
c
a
![Page 31: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/31.jpg)
13C Nuclear Magnetic Resonance
Carbonyl Compounds
aldehydes & ketones 185-220 ppm carboxylic acids, esters, amides, etc. 155-185 ppm nitriles 110-140 ppm
![Page 32: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/32.jpg)
13C Nuclear Magnetic Resonance
Aldehydes & Ketones
2-hexanone 205-220 ppm
185-200 ppm
chemical shifts
R CO
H
R CO
R'
CH3 CO
CH2-CH2-CH2-CH3a
a
209.0
![Page 33: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/33.jpg)
13C Nuclear Magnetic Resonance
Carboxylic Acid Derivatives
methacrylic acid
175-185 ppm
165-175 ppm
chemical shifts
R CO
OR'
R CO
OH
165-175 ppmR CO
NR'2
CH2CCH3
CO
HOa
a
173.5
![Page 34: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/34.jpg)
13C Nuclear Magnetic Resonance
Carboxylic Acid Derivatives
heptyl acetate
175-185 ppm
165-175 ppm
chemical shifts
R CO
OR'
R CO
OH
165-175 ppmR CO
NR'2
CH3 COO-CH2CH2-CH2-CH2-CH2-CH2-CH3
a b
a 171.0
b 64.6
![Page 35: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/35.jpg)
13C Nuclear Magnetic Resonance
Amides
N-methyl-6-hexanelactam
175-185 ppm
165-175 ppm
chemical shifts
R CO
OR'
R CO
OH
165-175 ppmR CO
NR'2
a
175.7 d
36.9
c
51.3 N
OCH3ab
c
d b
35.7
![Page 36: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/36.jpg)
13C Nuclear Magnetic Resonance
Nitriles
hexanenitrile
119.9
110-140 ppm
chemical shifts
R C N
a
C NCH3CH2CH2CH2a
![Page 37: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/37.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to Deuterium
multiplicity
relative intensity
multiplicity = 2nI + 1
where: n = # of nuclei I = spin
Cb
Da
Jab = 45 Hz
![Page 38: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/38.jpg)
13C Nuclear Magnetic Resonance
Solvent Peaks
CDCl3 D3C(S=O)CD3
![Page 39: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/39.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to 19F
fluorotribromomethane
1J = 370 Hz
C Cb
FCa
F
JFb = ~50 HzJFa = ~350 Hz
![Page 40: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/40.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to 19F
2,2,2-trifluoroethanol (proton decoupled)
1J = 278 Hz
2J = 35 Hz
C Cb
FCa
F
JFb = ~50 HzJFa = ~350 Hz
![Page 41: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/41.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to 19F
commonly observed systems
C Cb
FCa
F
JFb = ~50 HzJFa = ~350 Hz
F3C SO
OROF3C
C OR
O
trifluoroacetates trifluoromethanesulfonates(triflates)
![Page 42: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/42.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to 31P
tetramethylphosphonium chloride (proton decoupled)
1J = 56 Hz
C Cb
PCa
P
JPa, JPb variable
![Page 43: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/43.jpg)
13C Nuclear Magnetic Resonance
Heteronuclear Coupling to 31P
dimethyl methylphosphonate (proton decoupled)
2J = 6 Hz 1J = 144 Hz
C Cb
PCa
P
JPa, JPb variable
![Page 44: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/44.jpg)
1H Nuclear Magnetic Resonance
1. Get an Overview • identify any reference solvents in proton decoupled spectrum 2. Symmetry: • count the number of carbons (remember 13C is not integrated) • verify carbon count based on the molecular formula • is there any symmetry?
- rarely see overlap of peaks in absence of symmetry - ok to see fewer carbons (if reasonable); not okay to have more!
3. Chemical Shift: • determine the chemical shift of each resonance in the spectrum
- what functional groups may be present - consider the presence of heteroatoms 4. If Needed Collect DEPT Data • determine how many Hs are on each carbon 5. Put it all Together: • often helpful to consider 1H NMR data simultaneously
How to Interpret a 13C NMR Spectrum
![Page 45: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/45.jpg)
1H Nuclear Magnetic Resonance
Reporting 13C NMR Data (1H decoupled)
CH3CH2CH2CH2CH2C≡N
13C NMR (25 MHz, CDCl3) δ 119.9, 30.9, 25.2, 22.0. 17.1, 13.8.
119.9030.8725.2121.9617.1113.78
2619701000920814950
ppm Int
![Page 46: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/46.jpg)
1H Nuclear Magnetic Resonance
Reporting 13C NMR Data (1H decoupled)
13C NMR (25 MHz, CDCl3) δ 119.9, 30.9, 25.2, 22.0. 17.1, 13.8.
frequency (1/4 1H frequency)
list chemical shift of each peak to 1 decimal place*
solvent
*if two peaks round to same value, can add second decimal place (e.g. 69.87, 69.89);
![Page 47: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/47.jpg)
![Page 48: C Nuclear Magnetic Resonance - Chemistrychemistry.syr.edu/totah/che575/support/3a1/5-1.CNMR.pdf · 13C Nuclear Magnetic Resonance Chemical Shift Factors the Influence Chemical Shift](https://reader031.vdocuments.pub/reader031/viewer/2022013113/5af7b39e7f8b9ae948907cd9/html5/thumbnails/48.jpg)
13C Nuclear Magnetic Resonance
Chemical Shift