Chemical Spectroscopy photochemical organic reactions in micro reactors

• Applicants: Professor Dr.-Ing. Roland Dittmeyer, since 4/2022; Dr. Nicole Jung; Professor Dr. Hans Zappe
• Subject Area: Technical Chemistry ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2016 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274353615

Photochemistry is an important method for the production of important and valuable chemicals, especially for medical applications (for example, anti-cancer drugs). However the current methods often used to synthesise these compounds (batch synthesis in stirred reactors) is limited, it does not allow for effective up-scaling of the production, nor does it allow for the exploitation of unique reaction pathways where careful control of reaction time and exposure to light is required. To address these challenges, this project proposes a coordinated approach bringing together expertise in chemistry, process engineering and in situ analytic technqiues, to explore continuous flow photochemistry with an unprecendented level of real-time insight into reaction progress and conditions. The photoredox-catalysed acylation of indoles and indazoles, as well as the oxidative cyclization to acylindoles will be explored in flow micro reactors, utilizing in situ concentration sensors exploiting the variable IR absorption of the reaction/product mixtures, which will be detected using novel detectors based on Fabry-Perot filters. These filters will expand on initial discoveries in Phase 1 of the proposal, where static filters with stepped spacings between the multi-layer Bragg mirrors, were developed and proven effective in monitoring the progress of 2,1- Benzoxalonone synthesis. A major development will be to expand the capability of these sensors be replacing the static separators with liquid crystal elastomers, whose dimensions can be changed by heating. This will enable the sensors to be independently tuned to different target IR wavelengths, and making them adaptable to a range of different chemistries. These advanced sensors will be implemented in a number of standalone reactors looking at different reaction steps in the target chemistry, with a particular focus on obtaining useful reaction kinetic parameters for the separate reaction steps, under micro reactor flow photochemistry conditions. In the final part of the project, bringing together the different contributions will allow for the sensors to be deployed in multiple reactors, separators and other process units in a continuous flow, multi-step system, will a control system making full use of the real-time composition data provided by the IR sensors. Complementing this robust experimental work, will be a parallel modeling activity, where both analytical and numerical models of photochemistry in a microfluidic flow channel will be carried out. The model results will be compared to the obtained experimental results, providing additional insight into the flow photochemistry system and especially providing useful guidance in designing future flow photo reactors.

• DFG Programme: Research Units
• Subproject of: FOR 2383: Assessing and Controlling Dynamic Local Process Conditions in Microreactors via Novel Integrated Microsensors
• Ehemaliger Antragsteller: Bradley Ladewig, Ph.D., until 3/2022