N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
4.2 Alkenes
89
13 C Chemical Shifts of Enols (δ in ppm)
The carbon atom bonded to the enolic OH group is strongly deshielded so that its
shift is close to that of a carbonyl carbon. The other carbon atom of the double bond
is strongly shielded.
Enol:
Ketone:
13 C Chemical Shifts of Allenes (δ in ppm) [1]
R 1
R 2
R 3
a
b
c
–H
–H
–H
74.8
213.5
74.8
–CH 3
–H
–H
84.4
210.4
74.1
–CH 3
–CH 3
–H
93.4
207.3
72.1
–CH 3
–H
–CH 3
85.4
207.1
85.4
–CH 2 CH 3 –H
–H
91.7
208.9
75.3
–C(CH 3 ) 3 –C(CH 3 ) 3 –H
119.6
207.0
75.8
–CH=CH 2 –H
–H
93.9
211.4
75.1
–C– – – CH
–H
–H
74.8
217.7
77.3
–phenyl
–H
–H
94.4
210.0
78.8
–F
–H
–H
129.8
200.2
93.9
–Cl
–H
–H
88.8
207.9
84.5
–Br
–H
–H
72.7
207.6
83.8
–I
–H
–H
35.3
208.0
78.3
–OCH 3
–H
–H
123.1
202.0
90.3
–N(CH 3 ) 2 –H
–H
113.1
204.2
85.5
–C– – – N
–H
–H
67.4
218.7
80.7
–SCH 3
–H
–H
90.0
206.1
81.3
–COOH
–H
–H
88.1
217.7
80.0
C C C
R 1
R 2
R 3
H
c
O
HO
a 28.5
b 201.1
c 56.6
a 22.5
b 190.5
c 99.0
a 28.3
b 32.8
c 46.2
d 191.1
e 103.3
a 28.3
b 31.0
c 54.2
d 203.6
e 57.3
O
O
H
O
O
O
O
a
a
a
a
a
b
b
b
b
b
c
c
c
c
d
d
e
e