Heterogeneous photosensitisers and singlet oxygen in continuous flow:
Vapourtec presents application note 58, Visible-Light Singlet Oxygen Generation using Heterogeneous Photosensitisers in Continuous Flow.
Singlet oxygen is a highly energetic electronic state of oxygen. Singlet oxygen has a wide range of synthetic, biological and environmental applications. Generating singlet oxygen requires a photosensitiser and suitable light source to excite molecular, triplet-state oxygen. Producing singlet oxygen in batch is difficult because of light penetration limitations. Continuous flow is ideal for photochemical singlet oxygen reactions because of more efficient light penetration. Using the easy-Photochem it is possible to pump oxygen or compressed air directly from the regulator of a cylinder.
Using heterogeneous photosensitisers for generating singlet oxygen has clear advantages. Ease of separating by filtration and the subsequent reusability make heterogeneous photosensitisers an ideal choice for continuous flow photochemistry. This application note describes the use of a range of insoluble photoactive polymers as heterogeneous photosensitisers for continuous flow.
Heterogeneous photosensitisers and singlet oxygen in continuous flow
Using heterogeneous photosensitisers to generate singlet oxygen in continuous flow can be achieved in two ways. The heterogeneous photosensitiser can be pumped as a slurry along with oxygen (or air) through the UV-150 continuous flow photochemical reactor equipped with the appropriate light-source. Its is also possible to isolate the heterogeneous photosensitiser in the Vapourtec immobilised photocatalyst reactor and flow the reagent solution and oxygen through it.
In this application, the conversion of α-terpinene to ascaridole was used to indirectly detect the formation of singlet oxygen in continuous flow. The production of singlet oxygen in continuous flow was optimised using the two methods, and the heterogeneous photocatalyst stability was investigated. Once optimised, the singlet oxygen was used for the aerobic oxidation of boronic acids to phenols, and to degrade two environmental pollutants: bis-phenol A and cimetidine.
This application note describes:
- Production of singlet oxygen in continuous flow
- The use of the UV-150 photochemical reactor for heterogeneous dispersions
- Use of heterogeneous photocatalysts as slurries and packed beds in continuous flow
- Easy handling of a complex flow stream of solid, liquid and gas