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
Mass spectrometry sheds new light on thallium poisoning cold case
14.12.2018 | University of Maryland
Protein involved in nematode stress response identified
14.12.2018 | University of Illinois College of Agricultural, Consumer and Environmental Sciences
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy