N
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
136
4 13 C NMR
4.11.2 Ketones
Additivity Rule for Estimating the 13 C Chemical Shifts of Ketone Carbon Atoms (δ in ppm)
δ C=O = 193.0 + ∑ Z i
–C β –C α –C
ǁ
O
–C α –C β –
Substituent i
Z α
Z β
–C
6.5
2.6
–CH=CH 2
-0.8
0.0
–CH=CH–CH 3
0.2
0.0
–phenyl
-1.2
0.0
13 C Chemical Shifts of Ketones (δ in ppm)
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
O
H 3 C
CH 3
O
O
O
O
O
206.6
211.8
206.7
206.8
218.0
209.4
196.9
195.2
197.5
137.1
128.0
213.5
210.7
183.6
207.9
215.1
207.6
30.7
29.4
25.7
27.6
25.7
51.5
137.4
137.8
29.0
128.6
130.1
26.6
128.4
128.2
26.3
132.9
132.2
32.4
81.9
78.1
24.5
26.5
35.5
8.0
28.6
27.5
29.3
7.0
17.5
35.2
45.2
43.5
31.9
13.5
23.8
14.0
27.5
29.9
41.6
38.0
18.2
17.8
10.3
21.1
45.6
44.3