N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
4.1 Alkanes
85
Coupling through more than one bond (|J CH | in Hz)
The coupling constants can be estimated from the corresponding 1 H- 1 H coupling
constants [2]: J CH ≈ 0.62 J HH
Typical values:
Examples:
2 J CH 1– 6
1 H–CH 2 – 13 CH 3
4.5
3 J CH 0–10
1 H–CH 2 –CH 2 – 13 CH 3 5.8
The 13 C- 1 H coupling constants for coupling across three bonds depend on the
dihedral angle in the same way as the vicinal 1 H- 1 H coupling constants (see Chapter
5.1.2):
≈ 6
≈ 0
≈ 9
13 C- 13 C Coupling Constants (|J CC | in Hz)
The 13 C- 13 C coupling constants for coupling over three bonds depend on the dihedral angle in the same way as the vicinal 1 H- 1 H (see Chapter 5.1.2) and 13 C- 1 H
coupling constants. Maximum values of approximately 4–6 Hz are observed for
dihedral angles of 0 o and 180 o and minimal values around 0 Hz at 90 o .
4.1.3 References
[1] A. Fürst, E. Pretsch, W. Robien, A comprehensive parameter set for the prediction of the 13 C NMR chemical shifts of sp 3 -hybridized carbon atoms in organic
compounds, Anal. Chim. Acta 1990, 233, 213.
[2] J.L. Marshall, Carbon-Carbon and Carbon-Proton NMR Couplings, Verlag
Chemie International, Deerfield Beach, FL, 1983.
H
N
O
CH 3
CH 3
H 3 C
O CH 3
H 3 C
CH 3
O
H
13
C
H
13
C
H
13
C
H 3 C CH 3
OH
a
a
a
a
a
b
b
b
b
b
c
c
d
1 J 34.6
2 J ab 2.4
2 J ab 16.1
1 J ab 34.6
2 J ac 4.6
3 J ad 4.6
2 J bd <1
2 J ab 0.5
2 J ac 4.9
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
4.1 Alkanes
85
Coupling through more than one bond (|J CH | in Hz)
The coupling constants can be estimated from the corresponding 1 H- 1 H coupling
constants [2]: J CH ≈ 0.62 J HH
Typical values:
Examples:
2 J CH 1– 6
1 H–CH 2 – 13 CH 3
4.5
3 J CH 0–10
1 H–CH 2 –CH 2 – 13 CH 3 5.8
The 13 C- 1 H coupling constants for coupling across three bonds depend on the
dihedral angle in the same way as the vicinal 1 H- 1 H coupling constants (see Chapter
5.1.2):
≈ 6
≈ 0
≈ 9
13 C- 13 C Coupling Constants (|J CC | in Hz)
The 13 C- 13 C coupling constants for coupling over three bonds depend on the dihedral angle in the same way as the vicinal 1 H- 1 H (see Chapter 5.1.2) and 13 C- 1 H
coupling constants. Maximum values of approximately 4–6 Hz are observed for
dihedral angles of 0 o and 180 o and minimal values around 0 Hz at 90 o .
4.1.3 References
[1] A. Fürst, E. Pretsch, W. Robien, A comprehensive parameter set for the prediction of the 13 C NMR chemical shifts of sp 3 -hybridized carbon atoms in organic
compounds, Anal. Chim. Acta 1990, 233, 213.
[2] J.L. Marshall, Carbon-Carbon and Carbon-Proton NMR Couplings, Verlag
Chemie International, Deerfield Beach, FL, 1983.
H
N
O
CH 3
CH 3
H 3 C
O CH 3
H 3 C
CH 3
O
H
13
C
H
13
C
H
13
C
H 3 C CH 3
OH
a
a
a
a
a
b
b
b
b
b
c
c
d
1 J 34.6
2 J ab 2.4
2 J ab 16.1
1 J ab 34.6
2 J ac 4.6
3 J ad 4.6
2 J bd <1
2 J ab 0.5
2 J ac 4.9