Photosensitized Oxidation of Oxopurines by Rose Bengal
Photosensitized oxidations of oxopurines (OP) as caffeine, theophylline, theobromine and 1,3,7-trimethyluric acid (TMU) by Rose Bengal were investigated. In all cases photooxidations occur by a type II mechanism. Reactive and nonreactive 1O2 quenching rate constants by OP were determined in differen...
Guardado en:
| Autores principales: | , , |
|---|---|
| Formato: | JOUR |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00318655_v68_n4_p467_Murgida |
| Aporte de: |
| Sumario: | Photosensitized oxidations of oxopurines (OP) as caffeine, theophylline, theobromine and 1,3,7-trimethyluric acid (TMU) by Rose Bengal were investigated. In all cases photooxidations occur by a type II mechanism. Reactive and nonreactive 1O2 quenching rate constants by OP were determined in different solvents. Based on the correlations of the rate constants with different solvent parameters (α, β, ET[30], AN, DN, π*, ∈), the initial formation of an exciplex between 1O2 and OP is proposed that evolves to a zwitterionic transition state. Some reaction products were characterized, among them 3-methyl-5-(methylamine)-1,5-dehydrohydantoin was obtained as the main photooxidation product of TMU. A reaction mechanism is proposed for the formation of this and other reaction products. |
|---|