Traditional methods for downstream processing of chemical reactions can be time-consuming and inefficient as reactions usually need quenching and further purification (a process that typically requires large quantities of solvents). While in batch mode, operations that involve slurries and solid precipitates can be accommodated using appropriate solid work-up facilities; serious problems can arise such as fouling and blocking during continuous flow mode operations or during telescoped reaction processes. Since flow chemistry and microreactor technology are making a significant impact on the praxis of organic synthesis, we have devised simple, but effective prototype devices to overcome some of the problems associated with flow chemistry methods when slurries or solid particulates are involved.
The first of these we define as the MFIFM (magnetic field induced flow mixer) shown schematically above and in use (below). This new device, designed for agitating and lateral mixing in tubular reactors has proven useful in a number of experiments conducted in flow .
Above: A schematic and picture of the setup for measuring diffusion/ mixing in
flow using a Syrris Asia syringe pump and Mettler Toledo ReactIR FD.
We have also investigated the use of the AM Technology Coflore® agitating cell reactor which uses a transverse mixing motion to keep solids in suspension . The flow device delivered 208 g of N-iodomorpholinium hydroiodide salt over a 9 hour period (equating to 3.88 kg/week) under optimized conditions. The reactor is suitable for the medium-scale (5 kg) processing of solid-forming reactions and appears to offer the potential for a variety of more complex applications.
Also see our work on ultrasound for alternative mixing solutions.
1. Continuous stream processing: a prototype magnetic field induced flow mixer Green Process. and Synth. 2012, 1, 11-18
P. Koos, D.L. Browne and S.V. Ley*
2. Continuous flow processing of slurries: evaluation of an agitated cell reactor Org. Proc. Res. Dev. 2011, 15, 693-697
D.L. Browne, B.J. Deadman, R. Ashe, I.R. Baxendale, S.V. Ley*