N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
4.3 Alkynes
91
4.3 Alkynes
4.3.1 Chemical Shifts
13 C Chemical Shifts of Alkynes (δ in ppm)
Substituent R
a
b
–H
71.9
71.9
–CH 3
80.4
68.3
–CH 2 CH 3
85.5
67.1
–CH 2 CH 2 CH 3
84.0
68.7
–CH 2 CH 2 CH 2 CH 3
83.0
66.0
–CH(CH 3 ) 2
89.2
67.6
–C(CH 3 ) 3
92.6
66.8
–cyclohexyl
88.7
68.3
–CH 2 OH
83.0
73.8
–CH=CH 2
82.8
80.0
–C– – – C–CH 3
68.8
64.7
–phenyl
84.6
78.3
–OCH 2 CH 3
90.9
26.5
–SCH 2 CH 3
72.6
81.4
–CHO
81.8
83.1
–COCH 3
81.9
78.1
–COOH
74.0
78.6
–COOCH 3
74.8
75.6
Additivity rule for estimating the chemical shifts of sp-hybridized carbon atoms in
alkynes: see [1].
C
O
S
O
||
C
a b
R C C H
68.3 80.4 3.7
65.4 74.4
78.3 84.6
132.1 128.1
128.2
67.1 85.5 12.3 13.8
80.0 82.8 117.3 129.2
68.7 84.0 20.6 22.2 13.8
64.7 68.8
3.9
H C C CH 3
H C C CH 2 CH 3
H C C CH 2 CH 2 CH 3
H C C CH CH 2
C
C
H
122.3
H C C C C CH 3