464105 Automated Oscillatory Photochemical Reactor for High Throughput Studies of Visible-Light Photoredox Catalysis
In this project, capitalizing on the removed residence time limitation and enhanced mixing and mass transfer advantages of oscillatory flow strategy,4,5 a microscale photochemistry platform is developed for in-flow studies of visible-light photoredox catalysis. Position of the formed droplet (micro-reaction vessel) at the inlet and outlet of the oscillatory flow reactor is detected through a single-point optical detection, integrated within a custom-machined aluminum chuck. The optical feedback provided through the single-point position detection allows for automated switching of the flow direction of the carrier phase to ensure the droplet is always under the same irradiation intensity over the course of the photoredox catalysis process.
The developed experimental platform allowed for the effect of irradiation light intensity on the yield (obtained using in-flow LC/MS) and selectivity of the photoredox catalysis to be precisely characterized by automatic tuning of the irradiation power of the high power LED (through LabView). In addition, utilizing gas as the carrier phase in both sides of a droplet that is pre-formed via a computer-controlled liquid handler (containing the desired photocatalyst) provided sufficient gas molecules during the photoredox catalysis using a reactive gas as an oxidant (e.g., oxygen). Through adjusting the pressure of the carrier phase, the effect of gas concentration (e.g., oxygen pressure) on the photoredox catalysis (e.g., oxidative hydroxylation of phenylboronic acids) was studied.
The proposed experimental setup enables material efficient high-throughput screening and optimization of continuous (e.g., reaction time and concentration of the photocatalyst) and discrete (e.g., different metal complexes, and reaction solvents) parameters associated with a photoredox catalysis process using only 20 μL volume of the solution mixture per experimental condition. The obtained optimized parameters (e.g., photocatalyst molecule structure, concentration, solvent, irradiation power, and reaction time) will then be employed for large-scale (numbered up) continuous synthesis of the desired product under a similar characteristic length scale.
(1) Prier, C. K.; Rankic, D. A.; MacMillan, D. W. C. Chemical Reviews 2013, 113, 5322-5363.
(2) Zou, Y.-Q.; Chen, J.-R.; Liu, X.-P.; Lu, L.-Q.; Davis, R. L.; Jørgensen, K. A.; Xiao, W.-J. Angewandte Chemie 2012, 124, 808-812.
(3) Tucker, J. W.; Zhang, Y.; Jamison, T. F.; Stephenson, C. R. J. Angewandte Chemie International Edition 2012, 51, 4144-4147.
(4) Abolhasani, M.; Coley, C. W.; Jensen, K. F. Analytical Chemistry 2015, 87, 11130-11136.
(5) Abolhasani, M.; Bruno, N. C.; Jensen, K. F. Chemical Communications 2015, 51, 8916-8919.