Miniaturization is invading the world of chemical syntheses. Since typical chemical syntheses take place in several reaction steps with various separation or purification steps in between, microchemistry has almost always been limited to one-step reactions or sequences of reactions requiring no purification between steps.
Researchers at the Massachusetts Institute of Technology (MIT) have now produced an integrated multiple-step microscale production line. As reported in the journal Angewandte Chemie, their process includes three reaction steps and two separation processes (one gas–liquid and one liquid–liquid separation). Because it is arranged in a microscale reaction network, it is even possible to configure this process so that related compounds can be simultaneously produced in parallel.
To fully exploit the potential of microscale reaction technology, it is crucial to integrate the necessary separation steps. A team headed by Klavs F. Jensen has recently developed an efficient microfluidic separation technique and has now integrated this concept into a continuously operating, three-step reaction system. Microscale separations are driven by different principles than separations at normal scale, because in microfluidic systems, surface tension forces dominate over gravity.
This is how the microfluidic separation works: A porous separation membrane made of a fluoropolymer is coated with the organic phase of the mixture, which can “sneak through” the fine pores in the membrane. The aqueous phase to be separated off cannot coat the pores that have already been coated by the organic phase, because the two liquids are not miscible; the water can thus not pass through the membrane. The second separation, a gas–liquid separation, is based on the same principle: In this case, the liquid, which contains the intermediate product, wets the membrane and passes through the pores. Meanwhile, the coated membrane blocks the nitrogen gas that is released during the reaction.
To demonstrate their system, the researchers chose the synthesis of carbamates, compounds that are used as pesticides, among other things, and are important building blocks and reagents in chemical syntheses. The three-step synthesis used to make carbamates (the Curtius Rearrangement) involves intermediate products (azides, isocyanates) that have the potential to be dangerous, since some of these types of compounds pose an explosive or health hazard. The advantage of the microscale reaction system is that these intermediates are formed in situ and are then immediately consumed, so they don’t need to be isolated or stored.
If, after the second separation step, the product stream is divided and fed into multiple microreactors, each with a different reagent, a series of different but related carbamates can be produced in parallel.
Author: Klavs F. Jensen, Massachusetts Institute of Technology, Cambridge (USA), http://web.mit.edu/CHEME/people/faculty/jensen.html
Title: Multistep Continuous-Flow Microchemical Synthesis involving Multiple Reactions and Separations
Angewandte Chemie International Edition 2007, 46, No. 30, 5704–5708, doi: 10.1002/anie.200701434
Klavs F. Jensen | Angewandte Chemie
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences