“Flow chemistry,” also called “continuous flow chemistry” or “plug flow chemistry,” is used to describe a range of chemical reactions that occur in a continuously flowing stream as contrasted to classic static batch reactor systems. What the two have in common is the ‘reaction time’.
Full Answer
Why are flow reactors better than batch reactors?
Flow reactors have excellent heat transfer when compared with batch reactors. This is because the surface are to volume ration of flow reactors is much greater than that of batch reactors.
What are some examples of organometallic reagents?
This paper describes several examples of the use of organometallic reagents in a Vapourtec flow chemistry system. These include n-butyllithium, Grignard reagents, and DIBAL-H. Examples are reported over several hours of continuous pumping. Multigram quantities of products are produced. The highlight of the paper is an approach to the telescoped synthesis of (E/Z)-tamoxifen. Organometallic reagent-mediated transformations are used.
What is flow chemistry?
Flow chemistry is also known as continuous flow or plug flow chemistry. It involves a chemical reaction run in a continuous flow stream. The process offers potential for the efficient manufacture of chemical products. Significant breakthroughs using flow chemistry systems are in production of Tamoxifen (Breast Cancer) and Artemisinin (Malaria).
How is reaction time determined?
Reaction time is determined by the time the reagents take to flow through the reactor. This period is called the residence time.
What is a reactor?
The reactor can be a simple pipe/tube or a complex micro-structured device. The mixing device and reactor are maintained at the precise temperature to promote the desired reaction. The reactants may also be exposed to an electrical flux or a photon flux to promote an electrochemical or photochemical reaction.
What is the most versatile flow chemistry system?
The R-Series is undoubtedly the most versatile, modular flow chemistry system available today.
Can flow reactors have back mixing?
Flow reactors can be arranged to have very little or even no back-mixing
Why are micro flow reactors important?
The smaller scale of micro flow reactors or microreactors can make them ideal for process development experiments. Although it is possible to operate flow processes at a ton scale, synthetic efficiency benefits from improved thermal and mass transfer as well as mass transport.
How does flow chemistry change from serial to parallel?
The process development change from a serial approach to a parallel approach. In batch the chemist works first followed by the chemical engineer. In flow chemistry this changes to a parallel approach, where chemist and chemical engineer work interactively. Typically there is a plant setup in the lab, which is a tool for both. This setup can be either commercial or non commercial. The development scale can be small (ml/hour) for idea verification using a chip system and in the range of a couple of liters per hour for scalable systems like the flow miniplant technology. Chip systems are mainly used for liquid-liquid application while flow miniplant systems can deal with solids or viscous material.
Why are microwave reactors used?
Microwave reactors are frequently used for small scale batch chemistry. However, due to the extremes of temperature and pressure reached in a microwave it is often difficult to transfer these reactions to conventional non-microwave apparatus for subsequent development, leading to difficulties with scaling studies.
What are some examples of flow reactors?
Some examples of flow reactors are spinning disk reactors; spinning tube reactors; multi-cell flow reactors; oscillatory flow reactors; microreactors; hex reactors; and 'aspirator reactors'. In an aspirator reactor a pump propels one reagent, which causes a reactant to be sucked in. This type of reactor was patented around 1941 by the Nobel company for the production of nitroglycerin .
How is residence time determined?
Residence time: In batch production this is determined by how long a vessel is held at a given temperature. In flow the volumetric residence time is given by the ratio of volume of the reactor and the overall flow rate, as most often, plug flow reactors are used.
How difficult is it to run experiments in continuous flow?
As discussed above, running experiments in continuous flow systems is difficult, especially when one is developing new chemical reactions, which requires screening of multiple components, varying stoichiometry, temperature and residence time. In continuous flow, experiments are performed serially, which means one experimental condition can be tested. Experimental throughput is highly variable and as typically five times the residence time is needed for obtaining steady state. For temperature variation the thermal mass of the reactor as well as peripherals such as fluid baths need to be considered. More often than not, the analysis time needs to be considered .
What is reaction stoichiometry?
Reaction stoichiometry: In batch production this is defined by the concentration of chemical reagents and their volumetric ratio. In flow this is defined by the concentration of reagents and the ratio of their flow rate.
