NMR Spectroscopy

13C Substituent Increments for Alkanes and Cycloalkanes

terminal:
 internal:
Substituent Y a b g a b g
-D    -0.4     -0.1  0
-CH3  9 10 -2   6   8 -2
-CH=CH2 20   6   -0.5       -0.5
-CCH    4.5     5.4   -3.5       -3.5
-C6H5 23   9 -2 17   7 -2
-CHO 31   0 -2      
-C(O)CH3 30   1 -2 24   1 -2
-CO2H 21   3 -2 16   2 -2
-CO2R 20   3 -2 17   2 -2
-C(O)NH2 22     2.5   -0.5       -0.5
-CN  4   3 -3   1   3 -3
-NH2 29 11 -5 24 10 -5
-NHR 37   8 -4 31   6 -4
-NR2 42   6 -3     -3
-NO2 63   4   57   4  
-OH 48 10 -5 41   8 -5
-OR 58   8 -4 51   5 -4
-OC(O)CH3 51   6 -3 45   5 -3
-F 68   9 -4 63   6 -4
-Cl 31 11 -4 32 10 -4
-Br 20 11 -3 25 10 -3
-I -6 11 -1   4 12 -1

Example 1:

dC1 = 13.4 + 8 = 21.4 ppm
Observed: 22.6 ppm
dC2 = 25.2 + 41 = 66.2 ppm
Observed: 68.7 ppm
dC3 = 25.2 + 8 = 33.2 ppm
Observed: 32.0 ppm
dC4 = 13.4 + (-5) = 8.4 ppm
Observed: 9.9 ppm

Example 2:

dC1 = 13.4 + 48 = 61.4 ppm
Observed: 61.4 ppm
dC2 = 25.2 + 10 = 35.2 ppm
Observed: 35.0 ppm
dC3 = 25.2 + (-5) = 20.2 ppm
Observed: 19.1 ppm
dC4 = 13.4 = 13.4 ppm
Observed: 13.6 ppm

Example 3:

dC1 = 15.8 + 20 = 35.8 ppm
Observed: 35.7 ppm
dC2 = 16.3 + 11 = 27.3 ppm
Observed: 26.8 ppm
dC3 = 15.8 + (-3) = 12.8 ppm
Observed: 13.2 ppm

Return to: NMR Spectroscopy Page