Flow Photochemistry

Microstructure and visible light increase the efficiency of photochemical syntheses

Visible light for continuous flow photochemistry (CarbonCat project)
© Fraunhofer IMM
Visible light for continuous flow photochemistry (CarbonCat project)

Synthetic organic photochemistry has been extensively explored over the past century, often paving the way for the preparation of complex organic molecules that were not accessible through the classical route of thermal chemistry. Several photochemical syntheses have found their way into industrial applications for the production of everyday chemicals. However, until recently, photochemistry has not been fully exploited as a synthetic method in organic chemistry. With the emergence of novel photocatalytic and photophysical concepts for the use of visible light, the research field of synthetic organic photochemistry has developed into an extremely diverse and widely recognized synthetic method in recent years. In parallel, continuous-flow chemistry and micro process technology have become established tools in chemical synthesis and have proven to be perfect partners for the advancement of photochemistry in academic and industrial research.

Microstructured flow reactors are ideal for carrying out photochemical syntheses by bringing the incident light into perfect contact with the liquid and gaseous phases and solid catalysts in the microstructures. A precise control of the photochemical process takes place via an exactly defined irradiation time of the process streams in the channels or capillaries through their flow rate. We use energy-efficient LED technology for wavelength-selective irradiation in the synthesis. The small size of the light emitters available today allows these light sources to be specifically adapted to a wide variety of microreactor architectures. You can get an up-to-date overview of our reactors and laboratory systems for continuous photosynthesis here:

Reactors & Plants


Offer to our customers

In addition to the development and manufacture of photomicroreactors and the associated synthesis plants, we also carry out feasibility studies for your desired synthesis process. We would also be happy to accompany you during the subsequent transfer of the evaluated process into continuous flow operation and to use our know-how in reactor and plant development up to the pilot scale.

We pay particular attention to the development of cascade reactions in continuous flow, for which we want to combine photochemical catalysis, e.g. with precious metal, organo- or biocatalysis and thus create a particularly large synergy for multi-stage syntheses.

Synergy through catalysis combinations for cascade reactions
© Fraunhofer IMM
Synergy through catalysis combinations for cascade reactions

We use materials and compounds known from the literature as common catalyst materials for photochemistry:

  • Metal-free sensitizers: Rose Bengal, Eosin Y, perylene and porphyrin dyes, riboflavins, …
  • Organometallic complexes with Ir, Ru, Cu, …
  • Metal oxides: TiO2, Bi2O3, BiVO4, ZnO, …

We are currently working on the following processes in photochemical synthesis:

  • In-situ generation of singlet oxygen
  • Photo-oxidations and photo-oxygenations
  • Cis-trans isomerizations
  • Fluorinations
  • Cyanations
  • C-C coupling reactions by photochemically activated diazonium salts

Do you want to optimize your photochemical processes and transfer them to continuous flow operation? Or are you just thinking about using photochemistry in your processes for the first time? Contact us! We are the right partner for you!

Our expertise for your benefit

  • Mild reaction conditions with visible light maximize your product quality through less degradation in the process solution.
  • Different reactivity of photochemistry vs. thermal chemistry enables new synthetic routes and products for your product portfolio.
  • High compatibility of photochemistry with other catalysis processes enables a targeted integration into your existing synthesis processes.
  • Clever reactor design ensures better process control.
  • Process intensification avoids unnecessary waste.
  • Intrinsic scale-up of flow reactors automatically leads to a cost reduction for your processes.

Cascade Reactions


Cascade reactions for the heterogeneously catalyzed synthesis of chiral fine chemicals in a continuously operated reactor system

Webinar "Photochemistry in flow as tool for sustainable syntheses"

(english version only)

More information about the topic

"Sustainable Chemistry in Flow"