dC1 = 123.3 + [ 10.6a + 7.2b - 1.5g] - [ 7.9a' + 1.8b' - 1.5g'] + S(steric corrections) ppm
where: a,b,g and a',b', g' are the number of carbon atoms in those positions relative to the carbon atom observed
Steric corrections are derived from the following table (use all that apply).
Cg-Cb- Ca-C1=C2-Ca'- Cb'-Cg'
Steric Corrections (ppm) |
|
| Ca and a' are trans (E-configuration) | 0 |
| Ca and a' are cis (Z-configuration) | -1.1 |
| Two alkyl substituents at C1 (two Ca) | -4.8 |
| Two alkyl substituents at C2 (two Ca') | 2.5 |
| Two or more alkyl substituents at Cb) | 2.3 |
 |
|
| dC1 = 123.3 + [10.6(2)] - [7.9(1)] + [(-4.8) + (-1.1)] | = 130.7 ppm |
| Observed: | 131.4 ppm |
| dC2 = 123.3 + [10.6(1)] - [7.9(2)] + [(2.5) + (-1.1)] | = 119.5 ppm |
| Observed: | 118.7 ppm |
 |
|
| dC1 = 123.3 + [0] - [7.9(1) + 1.8(2) - 1.5(1)] + [0] | = 113.3 ppm |
| Observed: | 112.9 ppm |
| dC2 = 123.3 + [10.6(1) + 7.2(2) - 1.5(1)] - [0] + [0] | = 146.8 ppm |
| Observed: | 144.9 ppm |
Return to: NMR Spectroscopy Page