Andrew Mansfield Head of Flow Chemistry, Syrris
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Famous chemistry professors are doing it. Magazines are writing about it. Students are focusing on it. Research and development chemists are perfecting reactions with it, and scale-up chemists are producing products with it.
You’ve undoubtedly heard about flow chemistry, but unless you’ve used our R&D100 Award-winning Asia Flow Chemistry System, you might still be wondering – what, exactly, is flow chemistry?
The basics of flow chemistry
Though it goes by a number of names – “plug flow chemistry”, “microchemistry”, and “continuous flow chemistry” – the principles of flow chemistry are the same.
Flow chemistry is the process of performing chemical reactions in a tube or pipe
What this means is that reactive components are flowed down temperature-controlled tubes or pipes and mixed together at a mixing junction; a radically different approach from the traditional chemistry method of performing reactions in glass flasks or jacketed reactors.
The differences between plug flow and continuous flow chemistry
Though often used interchangeably, there is a small difference between “plug flow chemistry” and “continuous flow chemistry”.
Continuous flow chemistry is just that – continuous. The reactive materials are continuously pumped with no breaks, resulting in a continuous stream of chemicals, and therefore a continuous stream of end product.
Plug flow chemistry is where alternating “plugs” of reactive materials and solvent are pumped, where each plug is considered as a separate entity. These plugs never meet so the conditions in which they go through the flow chemistry system (i.e. temperature and residence time) can be changed to observe how the reaction changes.
Intelligent systems, such as the Asia Flow Chemistry System, can automatically collect the individual plugs, sending the product into one collector and the solvent into another.
What is a mixing junction?
So what do we mean by a “mixing junction”? Essentially, it’s the equivalent of a round-bottomed flask or a jacketed reactor – it’s where the mixing occurs in a flow chemistry system.
The two (or more) separate tubes of reactive compounds are brought together and flowed through a single, temperature-controlled channel in order to mix them.
What types of mixing junctions are available?
Glass microreactor chips
Glass microreactor chips are the most commonly known type of reactor used in a flow chemistry system. A piece of glass is “etched” with a particular design (depending on the application); the design helps determines how wide the mixing channel is and how the mixing occurs. A longer channel enables a longer residence time than a shorter channel (assuming the pump flow rate is the same).
Glass microreactor chips are inserted into chip climate controllers which maintain a set temperature throughout the entire chip and are the perfect system for chemists just starting out in flow chemistry.
Tube reactors are effectively long tubes wrapped around a heated or cooled coil. The large length of the coil offers far longer residence times than glass microreactor chips (or much faster pump flow rate) if the application requires it.
Column reactors are glass tubes and allow the use of solid phase chemistry such as catalysts, solid-supported reagents, or scavengers.
So why are chemists adopting flow chemistry into their reactions?
There are a number of reasons chemists across all industries are introducing, or switching to, continuous flow chemistry.
In short, the main benefits are;
- Faster reactions
- Safer reactions
- Faster reaction optimization
- Fast serial library synthesis
- Reaction conditions not possible in batch
- Reactions are usually more selective
- Scale up is easier in flow than batch
- Easy integration of reaction analysis
- Reactions are easier to work-up in flow
When is continuous flow chemistry not the answer?
The importance of smooth flow
About Dr. Andrew Mansfield
Andrew was formerly a Research Chemist at Pfizer and spent much of his career focusing on introducing flow chemistry technologies, meaning Andrew is well placed to lead Syrris’ flow chemistry offering. Read Andrew’s bio here.
What is catalysis? What is a catalyst? How does catalysis work? And why would you want to perform catalysis in continuous flow? Flow Chemistry Applications Specialist, Neal, explains why chemists like to incorporate catalysts into their chemistry and the benefits they bring…
So why should your lab consider performing your chemistry using continuous flow chemistry techniques? Discover several reasons including faster and reactions, and accessing novel chemistries not possible in batch
With modern technology, you can automate your entire lab if you wanted to, from automated liquid handling and motorized pipettes through to robots labeling your samples. But the easiest place to start is the source of your reactions – your jacketed reactor.
When you break it down, flow chemistry is not as scary a prospect as it might seem. Photos in your favorite chemistry magazine may make it look complex, but all you really need is a pump, some tubes, and a mixing junction.