Abstract

Scaling Photochemistry Using Continuous-Flow Technology

Oliver Kappe, Professor, Karl Franzens University of Graz

Within the synthetic chemistry community, photochemistry has made significant recent impact, with a plethora of novel transformations reported. These take place by irradiation of: the substrate directly; an in situ-generated charge transfer complex; or a metal or organic photocatalyst. The implementation of synthetic photochemistry can already begin to meet the aims of green chemistry through two main principles: a) performing known disconnections under milder conditions, by using photons as a mild and traceless reagent to activate otherwise benign starting materials; b) enabling entirely new disconnections, which can complete target-oriented syntheses in fewer steps, for significant savings in resources, time, energy and waste.

Photochemistry in batch is generally limited by poor light penetration, therefore, scaling up to larger batch reactors is generally impractical. Performing photochemistry in continuous flow has been demonstrated as a widely suitable method to perform photochemical reactions on larger scales. ,  In this presentation a number of illustrative examples of flow photochemistry from our laboratories using different light sources and reactor technologies will be discussed, with special emphasis given to handling solids in flow and the synthesis of Active Pharmaceutical Ingredients (APIs).