Continuous Flow Photochemistry Research Articles

ChemInform Abstract: Photochemical Transformations Accelerated in Continuous‐Flow Reactors: Basic Concepts and Applications

AbstractReview: [130 refs.

Photochemical transformations accelerated in continuous-flow reactors: basic concepts and applications.

Continuous-flow photochemistry is used increasingly by researchers in academia and industry to facilitate photochemical processes and their subsequent scale-up. However, without detailed knowledge concerning the engineering aspects of photochemistry, it can be quite challenging to develop a suitable photochemical microreactor for a given reaction. In this review, we provide an up-to-date overview of both technological and chemical aspects associated with photochemical processes in microreactors. Important design considerations, such as light sources, material selection, and solvent constraints are discussed. In addition, a detailed description of photon and mass-transfer phenomena in microreactors is made and fundamental principles are deduced for making a judicious choice for a suitable photomicroreactor. The advantages of microreactor technology for photochemistry are described for UV and visible-light driven photochemical processes and are compared with their batch counterparts. In addition, different scale-up strategies and limitations of continuous-flow microreactors are discussed.

Continuous flow photochemistry.

Due to the narrow width of tubing/reactors used, photochemistry performed in micro- and mesoflow systems is significantly more efficient than when performed in batch due to the Beer-Lambert Law. Owing to the constant removal of product and facility of flow chemical scalability, the degree of degradation observed is generally decreased and the productivity of photochemical processes is increased. In this Personal Account, we describe a wide range of photochemical transformations we have examined using both visible and UV light, covering cyclizations, intermolecular couplings, radical polymerizations, as well as singlet oxygen oxygenations.

Continuous Flow Photochemistry for the Rapid and Selective Synthesis of 2’-Deoxy and 2’,3’-Dideoxynucleosides

A new photochemical flow reactor has been developed for the photo-induced electron-transfer deoxygenation reaction to produce 2′-deoxy and 2′,3′-dideoxynucleosides. The continuous flow format significantly improved both the efficiency and selectivity of the reaction, with the streamlined multi-step sequence directly furnishing the highly desired unprotected deoxynucleosides.

Scalable and Robust Synthesis of CpRu(MeCN)3PF6 via Continuous Flow Photochemistry

Abstract The preparation of CpRu(MeCN)3PF6 using an easily assembled continuous flow reactor is described. This scalable, reproducible method provides the title compound in excellent yield and purity, and eliminates the need for any purification steps. Under our optimized conditions, the residence time required for complete conversion was only 5 min at an initial substrate concentration of 0.06 M, as compared to a reaction time of 12–36 h for the batch process at 0.02 M. This threefold increase in concentration and significant decrease in reaction time increases the throughput and efficiency of the synthesis. Using the simple laboratory equipment described herein, ruthenium catalyst of >99% purity was produced with a throughput of 1.56 g/h (5 mL reactor), which is 10 times the highest reported throughput for the batch process.