Additivity Rules for π-π* Transitions of Enones
- Base Values:
- Acylic ketones: 215 nm
- 6-membered cylic: 215 nm
- 5-membered cylic: 202 nm
- Aldehydes: 210 nm
- Carboxylic acids and esters: 195 nm
- Increments:
- Alkyl Groups:
- α +10 nm
- β +12 nm
- γ +18 nm
- Polar Groups, -OH:
- α +35 nm
- β +30 nm
- -Cl:
- α +15 nm
- β +12 nm
- Double bond extending conjugation +30 nm
- For example:
Reference: R.M. Silverstein, G.C. Bassler, and T.C. Morrill, "Spectrometric Identification of Organic Compounds," 5th ed., Wiley, NY, 199l, pps. 302-303.