Reactor technology concepts for flow photochemistry

Synthetic organic photochemistry has been intensively carried out in the 20th century and paved the way to the preparation of complex organic molecules, which were not yet accessible via thermal chemistry. Several photochemical synthesis routes have found their way into industrial applications for the production of everyday commodities, but photochemistry was still underutilized until recently as a synthesis method in organic chemistry. With the advent of novel photocatalytic and photophysical concepts for the use of high power visible light, the research field of synthetic organic photochemistry has evolved to become a vivid and highly recognized technique in the last years. Fortunately, continuous flow technology has also become an increasingly accepted tool and has proved to be an excellent key player for the advancement of photochemistry in academic and industrial research settings. This Review provides an overview on the recent developments of continuous flow photoreactors and their application to photochemical syntheses under mild and defined process conditions.