Flow chemistry

One of the obvious areas where flow chemistry comes into its own is in the arena of catalysed reactions and continuous processing. An excellent example of this is the Suzuki reaction (for recent reviews on the Suzuki Cross-Coupling reaction, see Miura 2004 Beilina et al. 2004 ... 

Chebanov VA, Muravyova EA, Sakhno YI, Saraev VE, Kappe CO, Desenko SM (2009) Microwaves vs. ultrasonication towards control of chemoselectivity. Microwave and flow chemistry conference, Jolli Beach, Antigua, 52... 

The route is, however, important as it shows the possibility of passing from multistep sequences in batch that usually require intermediate isolation and purification in between steps to a continuous sequence using flow chemistry that produces the desired molecules requiring a minimum purification at the end and providing important savings in time and resources. 

Figure 11.3 Process flow diagram for cyanation flow chemistry operations.

The following examples are intended to give a wider view of what continuous processes are being developed. It highlights the use of flow chemistry for more complex structures. 

J. K., Lane, W., Mathewson, A., Berney, H., Application of magnetohydrodynamic actuation to continuous flow chemistry, Lab Chip 2002, 2, 224-230. 

The reasons to perform electrochemistry, in particular, electrosynthesis, in a microfluidic system are the following (Rode et al., 2009) (1) reduction of ohmic resistance in the electrochemical cell, by decreasing the distance between anode and cathode, (2) enhancement of mass transport by increase of electrode surface to cell volume ratio, also realized by small interelectrode gaps, (3) performing flow chemistry to establish single-pass conversion, and (4) coupling of cathode and anode processes, permitting simultaneous formation of products at both electrodes. The latter... 

A fifth reason for using microfluidics in electrochemistry would be the possibility to combine flow chemistry with an ultrafast mixer, which allows the generation and subsequent use of short-lived reactive ions or radicals, for example, in a "cation flow" process (Suga et al., 2001 Yoshida, 2008). Finally, a sixth reason for performing electrochemistry in a microfluidic system may be the desire to efficiently remove reaction heat (or joule heat due to high currents in combination with a high ohmic resistance) in fast electrochemical reactions (Yoshida, 2008). 

In this chapter we discuss the new speeding-up techniques, optimized during the last decade, such as solid-phase extraction, polymer-assisted solution-phase synthesis, microwave-assisted organic synthesis, and flow chemistry. The improvements obtained with these techniques are not limited to a subset of chemical reactions (e.g., the reported examples), but they are fully applicable to the entire set of chemistry involved in the synthetic drug discovery process. 

In flow chemistry, a chemical reaction is run in a continuously flowing stream pumps move solutions containing the reactants into a network of interconnecting tubes and, where tubes join one another, the fluids come into contact and the reaction takes place. In the realization of a flow process, then, technical and engineering aspects have the same importance as chemical considerations, even in laboratory scale. 

Methods of Conducting Flow Chemistry 4.2.3.1 On-Bead Synthesis... 

Flow Chemistry and Automation in the Synthesis of Drug-Like Molecules... 

Figure 11 Asymmetric catalysis using flow chemistry on sequentially linked columns...

In this article, we begin by reviewing the variety of problems associated with laboratory and flight investigations of hypersonic rarefied flows. Then a complete review of computational methodologies is provided. This includes both continuum and particle methods. The focus is on particle methods and details are provided on general concepts. Then, several of the most commonly employed chemistry models are described in detail. There are two components to any chemistry model the rate of chemical reaction, and the mechanics of chemical reaction. These are discussed separately. Models for gas-surface interaction and hybrid methods that use both continuum and particle descriptions of the gas flow are also briefly reviewed. Results are reviewed for hypersonic conditions in air applicable to the Space Shuttle and to ballistic missiles where both dissociation and exchange reactions are important. The behavior of rarefled flow chemistry models is first considered in a test cell environment. Then, the models are applied to... 

Bolton E. W., Lasaga A. C., and Rye D. M. (1999) Long-term flow/chemistry feedback in a porous medium with heterogeneous permeability kinetic control of dissolution and precipitation. Am. J. Sci. 299, 1-68. 

X.D. Wang, T.J. Cardwell, R.W. Cattrall, G.E. Jenkins, Pulsed flow chemistry. A new approach to the generation of concentration profiles in flow analysis, Anal. Commun. 

S.W. Lewis, P.S. Francis, K.F. Lim, G.E. Jenkins, X.-D. Wang, Pulsed flow chemistry a new approach to solution handling for flow analysis coupled with chemiluminescence detection, Analyst 125 (2000) 1869. 

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