Increment system for estimation of chemical shifts of alkene protons
Formula:
| Substituent | Igem | Icis | Itrans | comment |
| -H | 0 | 0 | 0 | |
| -alkyl | 0.45 | -0.22 | -0.28 | chain |
| -alkyl | 0.69 | -0.25 | -0.28 | 5 or membered ring |
| -CH2-aryl | 1.05 | -0.29 | -0.32 | |
| -CH2OR | 0.64 | -0.01 | -0.02 | |
| -CH2NR2 | 0.58 | -0.10 | -0.08 | |
| -CH2X | 0.70 | 0.11 | -0.04 | X=halogen |
| -CH2COR | 0.69 | -0.08 | -0.06 | |
| -C(R)=CR2 | 1.00 | -0.09 | -0.23 | diene |
| 1.24 | 0.02 | -0.05 | polyene | |
| -CCH | 0.47 | 0.38 | 0.12 | alkyne |
| -aryl | 1.38 | 0.36 | -0.07 | |
| -CHO | 1.02 | 0.95 | 1.17 | |
| -COR | 1.10 | 1.12 | 0.87 | enon |
| 1.06 | 0.91 | 0.74 | longer conjugation | |
| -COOH | 0.97 | 1.41 | 0.71 | acid |
| 0.80 | 0.98 | 0.32 | longer conjugation | |
| -COOR | 0.80 | 1.18 | 0.55 | ester |
| 0.78 | 1.01 | 0.46 | longer conjugation | |
| -CONR2 | 1.37 | 0.98 | 0.46 | |
| -COCl | 1.11 | 1.46 | 1.01 | |
| -CN | 0.27 | 0.75 | 0.55 | nitrile |
| -OR | 1.22 | -1.07 | -1.21 | saturated |
| -OR | 1.21 | -0.60 | -1.00 | unsaturated |
| OOCR | 2.11 | -0.35 | -0.64 | |
| -SR | 1.11 | -0.29 | -0.13 | |
| -SO2R | 1.55 | 1.16 | 0.93 | |
| -NR2 | 0.80 | -1.26 | -1.21 | saturated |
| -NR2 | 1.17 | -0.53 | -0.99 | unsaturated |
| =N-COR | 2.08 | -0.57 | -0.72 | |
| -NO2 | 1.87 | 1.32 | 0.62 | |
| -F | 1.54 | -0.40 | -1.02 | |
| -Cl | 1.08 | 0.18 | 0.13 | |
| -Br | 1.07 | 0.45 | 0.55 | |
| -I | 1.14 | 0.81 | 0.88 |
Example: Methyl methacrylate
