Additivity Parameters for 13
C Chemical Shifts in Substituted Benzenes*
| Substituent | Ipso** | Ortho | Meta | Para |
|---|---|---|---|---|
| H | 0.0 | 0.0 | 0.0 | 0.0 |
| CH3 | 8.9 | 0.7 | -0.1 | -2.9 |
| C2H5 | 15.6 | -0.4 | 0.0 | -2.6 |
| i -C3H7 | 20.2 | -2.5 | 0.1 | -2.4 |
| t -C4H9 | 22.0 | -3.4 | -0.4 | -3.1 |
| CH=CH2 | 9.5 | -2.0 | 0.2 | -0.5 |
| C6H5 | 13.1 | -1.1 | 0.4 | -0.2 |
| CF3 | 2.6 | -3.3 | -0.3 | 3.2 |
| OH | 26.9 | -12.7 | 1.4 | -7.3 |
| OCH3 | 31.4 | -14.4 | 1.0 | -7.7 |
| OC2H5 | 31.0 | -13.7 | 1.1 | -7.9 |
| SCH3 | 10.2 | -1.8 | 0.4 | -3.6 |
| C(O)H | 9.0 | 1.2 | 1.2 | 6.0 |
| Substituent | Ipso** | Ortho | Meta | Para |
|---|---|---|---|---|
| C(O)OH | 2.1 | 1.5 | 0.0 | 5.1 |
| C(O)CH3 | 9.1 | 0.1 | 0.0 | 4.2 |
| CN | -15.4 | 3.6 | 0.6 | 3.9 |
| NH2 | 18.0 | -13.3 | 0.9 | -9.8 |
| NHC(O)CH3 | 11.1 | -9.9 | 0.2 | -5.6 |
| N(CH3)2 | 22.6 | -15.6 | 1.0 | -11.5 |
| NO2 | 20.0 | -4.8 | 0.9 | 5.8 |
| F | 34.8 | -12.9 | 1.4 | -4.5 |
| Cl | 6.2 | 0.4 | 1.3 | -1.9 |
| Br | -5.5 | 3.4 | 1.7 | -1.6 |
| I | -32.0 | 10.2 | 2.9 | 1.0 |
| Si(CH3)3 | 13.4 | 4.4 | -1.1 | -1.1 |
| Sn(CH3)3 | 13.1 | 7.2 | -0.4 | -0.4 |
* Ppm relative to internal benzene. In CCl4, except for CH=CH2 (neat), N(CH3)2 (neat), Si(CH3)3 (neat), and Sn(CH3)3 (neat). Chemical shift of benzene: 128.5 ppm relative to TMS.
** Ipso refers to the carbon atom bearing the substituent.
Reference: Levy, Lichter and Nelson, pps. 111-112; Breitmaier and Voelter, pps. 256-258.