N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
179
5.2 Alkenes
179
Substituent R
Z gem
Z cis
Z trans
–S–
1.11
-0.29
-0.13
–S(O)–
1.27
0.67
0.41
–S(O) 2 –
1.55
1.16
0.93
–SCO–
1.41
0.06
0.02
–SCN
0.94
0.45
0.41
–SF
1.68
0.61
0.49
–CHO
1.02
0.95
1.17
–CO–
1.10
1.12
0.87
–CO– conjugated 2
1.06
0.91
0.74
–COOH
0.97
1.41
0.71
–COOH conjugated 2
0.80
0.98
0.32
–COOR
0.80
1.18
0.55
–COOR conjugated 2
0.78
1.01
0.46
–CON
1.37
0.98
0.46
–COCl
1.11
1.46
1.01
–P(O)(OCH 2 CH 3 ) 2
0.66
0.88
0.67
1) The increment "alkyl ring" is to be used if the substituent and the double bond are part of
a cyclic structure.
2) The increment "conjugated" is to be used if either the double bond and/or the substituent
are conjugated to other substituents.
3) The increment "aromatic, fixed" is to be used if the double bond conjugated to an aromatic ring is part of a fused ring (such as in 1,2-dihydronaphthalene).
Influence of cis- and trans-Substituents on the 1 H Chemical Shift of
Methyl Groups at the Double Bond in Isobutenes (δ in ppm )
S
O
||
C
P
H
COOCH 3
H 3 C
H 3 C
H
COCl
H 3 C
H 3 C
H
H 3 C
H 3 C
1.88
1.80
1.68
1.62
5.13
1.70
4.63
1.75
1.75
5.78
1.65
1.65
6.79
2.12
1.84
5.62
2.11
1.91
5.63
1.97
2.12
6.01
1.86
2.06
5.97
5.17
H
H
H 3 C
H 3 C
H
Br
H 3 C
H 3 C
H
COCH 3
H 3 C
H 3 C
H
OCOCH 3
H 3 C
H 3 C
H
H 3 C
H 3 C
H
CHO
H 3 C
H 3 C