NMR Nuclear Magnetic Resonance

1
NMR Nuclear Magnetic Resonance

• Heteronuclear NMR

Index
NMR-basics
H-NMR
NMR-Symmetry
Heteronuclear-NMR
2
Proton with Carbon-13 coupling
3
Proton with Fluorine-19 coupling
4
Fluorine-19Fluoroacetone
5
Phosphorus-31
6
Phosphorus-31 Coupling with 1H
7
Phosphorus-31 Coupling with 13C
8
Phosphorus-31
9
Phosphorus-31
28 Hz
8Hz
dt
10
Phosphorus-31
39 Hz
9 Hz
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
11
Silicon, Mercury, Carbon
12
N15 NMR
10 mm tube 25 in CDCl3 Inverse gated D115
s Total time 12 hrs
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
13
C-13 NMR
14
C-13 NMR Quantitative??

1. In C-13, some carbons can have long relaxation
   time If the relaxation delay is not long enough,
   the long relaxation carbons will not achieve full
   amplitude
2. NOEs varies for the various carbons
3. Number of data points used to record the data
   might not be sufficient
4. The efficiency of the pulse vary depending if a
   signal is in the center of the window or on the
   side.

15
Normal C13 measure time 1.5 hrsNOE present, no
integration possible
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
2
C2
1
3
3JCP 2.3
3JCP 5.5
2JCP 7.2
1JCP 201.3
C3
PCHO2
C1
1JCP
OCH2
CH3
16
C13-NMR
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
2
1
d
3
C13, H-coupled
dd
q
t
C2
PCHO2
C3
1JCP
C1
OCH2
CH3
17
C13 coupling to proton
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
2
1
3
3JC3-H2 7.9
2JC3-H2 5.4
C3-Cl
18
C13 extracting J values
Me
3JPC 5.5 Hz
CH2 selective dec.
Quartet CH3 split by P (doublet) Split by CH2
triplet
1JCH 127.7 Hz
19
C13 inverse gated integrationMeasuring time 28
hoursD1120 s
NMR From Spectra to Structures An Experimental
approachSecond edition (2007) Springler-Verlag Te
rence N. Mitchellm Burkhard Costisella
D1
off
20
Multiplicity detection
DEPT CH, CH3 CH2
APT CH, CH3 C , CH2
Normal C13
21
(No Transcript)
22
(No Transcript)
23
NOE and decoupler
24
(No Transcript)
25
Carbon-13 Shift
26
Carbon-13 Shift
Acid Amide Ester
Ketone Aldehyde
O
C O
C O
C O
C ? C
C
C C
CC
0
100
200
50
150
27
Alkanes
d -2.5 SnA
1 2 3 4 5
CH3-CH2-CH-CH2-CH3
CH3
6
dC1 -2.5 1a 1b 2g 1d
dC1 -2.5 9.1 9.4 2(-2.5) .3 11.3
dC2 -2.5 2a 2b 1g 2o(3o)
(Secondary carbon bound to tertiary)
dC2 -2.5 18.2 18.8 (-2.5) (-2.5) 29.5
dC3 -2.5 3a 2b 23o(2o)
dC3 -2.5 27.3 18.8 (-7.4) 36.2
dC6 -2.5 1a 2b 2g 1o(3o) 19.3
28
Alkanes
dC1 -2.5 1a 1b 2g 1d 11.3
dC2 -2.5 2a 2b 1g 2o(3o) 29.5
dC3 -2.5 3a 2b 23o(2o) 36.2
dC6 -2.5 1a 2b 2g 1o(3o) 19.3
C1
C2
C3
C6
2
3
1
6
29
Substituted Alkanes
CH3-CH2-CH2-CH2-CH3
13.9 22.8 34.7
g b a
CH3-CH2-CH-CH2-CH3
OH
CH 34.7 41 75.7 ppm
CH2 22.8 8 30.0 ppm
CH3 13.9 (-5) 8.9 ppm
30
CH 34.7 41 75.7 ppm
g b a
CH3-CH2-CH-CH2-CH3
CH2 22.8 8 30.0 ppm
OH
CH3 13.9 (-5) 8.9 ppm
31
Shift Calculation

• Select a suitable model
• Use proper substituent effects to predict the
  shifts of the various carbonsThis gives a crude
  estimate without taking into account the geometry
• For cyclohexanes, substituents effects are
  compiled in terms of axial/equatorial orientation

32
Cycloalkanes Cyclohexane
33
Alkenes Additivity rules
34
Unsaturated compounds Electronic Effects
Alkenes
d-
129.3
d
157
Allenes
75-97
200-215
Alkynes
65-90 ppm
23.2
89.4
35
Benzene Calculation
36
Nitro-4-Aniline
37
Example Benzene Calculation gt distinguish
isomers
38
H-NMR isomers
39
Example Benzene Calculation gt distinguish
isomers
Experimental shifts 152.5, 136.6, 131.7, 126.3,
121.9, 116.3
Subst. C1 ortho meta para Me 9.2 0.7 -0.1 -3.0 C
H(Me)2 20.2 -2.2 -0.3 -2.8 OH 26.9 -12.8 1.4 -7.
4
C1 128 9.2 2.8 1.4 135.8 C2 128 .7 -
0.3 7.4 121.0 C3 128 0.1 2.2 1.4
127.1 C4 128 3.0 20.2 12.8 132.4 C5
128 0.1 2.2 26.9 152.6 C6 128 0.7
0.3 12.8 115.6
C1 128 9.2 2.8 12.8 121.6 C2 128 .7
- 0.3 1.4 129.8 C3 128 0.1 2.2 - 7.4
118.3 C4 128 3.0 20.2 1.4 146.6 C5
128 0.1 2.2 - 12.8 112.9 C6 128 0.7
0.3 26.9 155.3
40
C1 128 9.2 2.8 1.4 135.8 C2 128 .7 -
0.3 7.4 121.0 C3 128 0.1 2.2 1.4
127.1 C4 128 3.0 20.2 12.8 132.4 C5
128 0.1 2.2 26.9 152.6 C6 128 0.7
0.3 12.8 115.6
41
C1 128 9.2 2.8 12.8 121.6 C2 128 .7
- 0.3 1.4 129.8 C3 128 0.1 2.2 - 7.4
118.3 C4 128 3.0 20.2 1.4 146.6 C5
128 0.1 2.2 - 12.8 112.9 C6 128 0.7
0.3 26.9 155.3
42
Carbonyls CO
Acid
Ester
43
Carbonyls COEsters, Acid chlorides, Anhydrides,
Amides, Carbamates
44
Carbonyls CO Ketones, Aldehydes
45
Coupling between 1H and 13C1JCH
One bond coupling is proportional to s
charactersp3 125 Hzsp2 165 Hzsp 250
Hz Electronegative subst. Increase JCH-OR gt J
140 HzCH-Cl gt J 150 Hz
46
Coupling between 1H and 13C sp3 1JCH
Increase of coupling values with the
electronegativity of the substituant CHZ Z
Li 1JCH 98 Hz Z C 1JCH 125-129 Hz Z
NR 1JCH 131-134 Hz Z S 1JCH 138 Hz Z
OR 1JCH 140 Hz Z Cl 1JCH 150 Hz Z
(OR)2 1JCH 162 Hz Z Cl2 1JCH 178 Hz
1JCH 161 Hz
1JCH 180 Hz
1JCH 134 Hz
1JCH 137 Hz
1JCH 150 Hz
47
Coupling between 1H and 13C sp2 1JCH
Increase of coupling values with the
electronegativity of the substituant CHZ
C-H 1JCH 157 Hz
1JCH 238 Hz
1JCH 172 Hz
1JCH 250 Hz
1JCH 200 Hz
1JCH 182 Hz
1JCH 202 Hz
48
Use of 1JCH
Extremely useful for molecules where 1JCH larger
than usual
Diagnostic for alkynes (250 Hz) , epoxides (180
Hz) , hemiacetal (162 Hz) and cyclopropane (161
Hz)
49
Coupling between 13C and 13C 1JCC
Measurable only on enriched compound Useful for
setting up pulse sequences like INADEQUATE
sp3
R-CH2-CH3 1JCC 35 Hz
1JCC 48 Hz
sp2
1JCC 44 Hz
1JCC 56 Hz
1JCC 54 Hz
1JCC 74 Hz
1JCC 74 Hz
1JCC 123 Hz
50
Coupling between 1H and 13C2JCH
Usually small and difficult to predict Typical
values -8 to 4 Hz
51
Coupling between 1H and 13C3JCH
Depend on dihedral angle between coupled nuclei
Karplus curve 0 angle 3JC-H 3-7 Hz 90 angle
3JC-H 0 Hz 180 angle 3JC-H 7-12 Hz
This behavior (Jcis lt Jtrans) is useful specially
in sp2 carbons to help distinguishing isomers
52
3J example of usage
Decouple OMe
53
C-13 Coupling with other nuclei than H
1JCD 20 Hz 1JCF -160 Hz 1JCN 6-8 Hz 1JP-H
gt600 Hz
54
15N NMRAmine
55
15N NMRAmide
56
15N NMRAromatic
57
29Si NMR
58
29Si H NMR
3JSiH-CH2 3.1 Hz
Si-H Septet
59
29Si H NMR
d 1JSi-H quintet 2JCH2-Si d 3JHSi-Si
Si-H Quintet
CH2 A B
60
19F NMR
Index
NMR-basics
H-NMR
NMR-Symmetry
Heteronuclear-NMR
Dynamic-NMR