Woodward-Fieser Rules for Dienes |
|||
| Homoannular (cisoid) |
Heteroannular (transoid) |
||
| Parent | l=253 nm | l=214 nm =217 (acyclic) |
|
| Increments for: | |||
| Double bond extending conjugation | 30 | 30 | |
| Alkyl substituent or ring residue | 5 | 5 | |
| Exocyclic double bond | 5 | 5 | |
| Polar groupings: | |||
| -OC(O)CH3 | 0 | 0 | |
| -OR | 6 | 6 | |
| -Cl, -Br | 5 | 5 | |
| -NR2 | 60 | 60 | |
| -SR | 30 | 30 | |
![]() |
||
| Transoid: | 217 nm | |
| Alkyl groups or ring residues: | 3 x 5 = | 15 nm |
| Calculated: | 232 nm | |
| Observed: | 234 nm | |
![]() |
||
| Cisoid: | 253 nm | |
| Alkyl groups or ring residues: | 2 x 5 = | 10 nm |
| Calculated: | 263 nm | |
| Observed: | 256 nm | |
![]() |
||
| Transoid: | 214 nm | |
| Alkyl groups or ring residues: | 3 x 5 = | 15 nm |
| Exocyclic double bond: | 5 nm | |
| Calculated: | 234 nm | |
| Observed: | 235 nm | |
![]() |
||
| Cisoid: | 253 nm | |
| Alkyl groups or ring residues: | 4 x 5 = | 20 nm |
| Exocyclic double bond: | 5 nm | |
| Calculated: | 278 nm | |
| Observed: | 275 nm | |
Return to: UV/Vis Spectroscopy Page