N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
4.6 Heteroaromatics
109
Effect of Substituents in Position 3 on 13 C Chemical Shifts of Monosubstituted
Pyridines (δ in ppm)
N
R
Substituent R
C-2
C-3
C-4
C-5
C-6
–CH 3
1.3
8.9
0.0
-0.9
-2.3
–CH 2 CH 3
-0.4
15.4
-0.8
-0.5
-2.7
–phenyl
-1.4
12.8
-1.8
-0.3
-1.3
–F
-11.5
36.1
-13.2
0.8
-3.9
–Cl
-0.3
8.1
-0.4
0.6
-1.4
–Br
2.1
-2.7
2.7
1.1
-0.9
–I
7.1
-28.5
8.9
2.3
0.3
–OH
-10.7
31.3
-12.4
1.2
-8.6
–OCH 3
-12.5
31.5
-15.9
0.1
-8.4
–OCOCH 3
-6.5
23.4
-7.0
-0.1
-3.2
–NH 2
-11.9
21.4
-14.4
0.8
-10.8
–NHCH 3
-13.6
23.1
-18.2
0.6
-11.9
–N(CH 3 ) 2
-14.0
23.3
-17.1
0.1
-11.6
–NO 2
-4.9
20.5
-5.1
0.0
4.9
–C– – – N
3.6
-13.8
4.2
0.5
4.2
–SH
-12.8
26.1
-11.3
7.3
-2.8
–SCH 3
-13.6
24.6
-11.7
10.6
-3.0
–CHO
2.4
7.8
-0.2
0.5
5.4
–COCH 3
3.5
8.5
-0.7
-0.2
0.0
–COOH
-6.4
13.0
11.1
4.3
-6.0
–COOCH 3
-0.6
1.0
-0.5
-1.8
1.8
–CONH 2
2.7
5.9
1.1
1.2
-1.5
–Si(CH 3 ) 3
2.7
9.1
3.0
-2.3
-1.2
–Ge(CH 3 ) 3
3.9
12.8
4.2
-0.4
-0.1
–Sn(CH 3 ) 3
5.9
13.0
7.1
0.1
-0.3
–Sn(n-C 4 H 9 ) 3
6.6
12.6
7.7
0.0
-0.4
–Pb(n-C 4 H 9 ) 3
7.1
21.7
8.5
0.9
-1.8
for R: H
δ C 2,6
= 149.8
δ C 3,
= 123.7
δ C 4
= 135.9
2
3
6
4
5
C
X
O
N
S
O
||
C
M