CPC CYTOS

Figure 4.22 Photograph of the CPC CYTOS system [74] (top) and working scheme [76] (bottom) (by courtesy of CPC).

Condensation of 1,3-diketones with hydrazines or hydroxyamines was conducted in a microflow system to give pyrazoles and isoxazoles in good yields [22]. High-throughput synthesis of pyrrole by the Paal-Knorr condensation of ethanolamine and acetonylacetone was achieved using the CPC CYTOS Lab System [23], The running of the system for 165 min resulted in 714 g of the pyrrole (Scheme 4.14). 

Palladium-catalyzed amination of aromatic halides, developed independently by Buchwald and Hartwig, is a useful tool for the construction of C—N bonds. Caravieilhes and coworkers reported using a microreador for aromatic amination [35]. With the use of CPC CYTOS Lab System, the reaction of p-bromotoluene with piperidine gave the desired coupling produd in quantitative yields with a residence time of 7.5 min (Scheme 4.24). 

The LCA methodology has been used by Krahsch and Kreisel to investigate the pros and cons of micro-reaction technology at the stage of process development. The motivation for this study was the question whether ecological improvements can be expected for the chosen model reaction performed in the micro-structured device Cytos produced by CPC Systems GmbH, Germany. Such improvements were the premise for the construction of a continuously operated pilot plant based on Cytos micro-reactors. 

Based on these positive results, a continuously operating Cytos Pilot Plant was constructed by CPC Systems GmbH and is used for fine chemical production. The results of the evaluation on production scale confirm those results obtained already during the process development stage, which have been discussed in detail elsewhere. ... 

Fig. la-e. Selected microreactors, a Stainless steel microreactor system designed by Ehrfeld Mikrotechnik. b Glass microreactor (Watts and Haswell 2005). c Stainless steel microreactor of the CYTOS Lab system (http //www.cpc-net.com/cytosls.shtml). d Silicon-based microreactor designed by Jensen (Ratner et al. 2005). e Glass microreactor of the AFRICA System... 

Stainless steel is the material of choice for process chemistry. Consequently, stainless steel microreactors have been developed that include complete reactor process plants and modular systems. Reactor configurations have been tailored from a set of micromixers, heat exchangers, and tube reactors. The dimensions of these reactor systems are generally larger than those of glass and silicon reactors. These meso-scale reactors are primarily of interest for pilot-plant and fine-chemical applications, but are rather large for synthetic laboratories interested in reaction screening. The commercially available CYTOS Lab system (CPC 2007), offers reactor sizes with an internal volume of 1.1 ml and 0.1 ml, and modular microreactor systems (internal reactor volumes 0.5 ml to... 

CPC (2007) Cytos Lab System, http //www.cpc-net.com/cytosls.shtml. Cited 5 February 2007... 

CPC developed a series of table-top micro reaction systems called CYTOS (Figure 4.22), SEQUOS and OPTIMOS based on a standardized platform. CYTOS is the basic laboratory system with internal and external modularity for high flexibility by running different chemical reactions. The internal modularity offers the realization of variable reaction times up to 45 min by using several residence time units. The external modularity provides a system configuration for a multi-step synthesis. CPC Systems individual connecting principle minimizes the dead volume in the system and provides the reaction with isothermal conditions through the whole system [74, 75]. 

The DABCO-promoted Baylis-Hillman reaction was run continuously using the CYTOS College System (CPC Systems GmbH) with yields comparable to those of the batch reaction and with a significant reduction in reaction time (Scheme 4.10) [14]. Coupled with the stopped-flow technique, an almost complete conversion was achieved. 

Another prodrug synthesis using a microfluidic reaction system is that of the antibiotic ciprofloxacin [10], A microreaction system developed by CPC systems (CYTOS) was used as a reaction apparatus. This system is the size of a videotape with a holdup of 1.8 ml. The high surface-to-volume ratio for the mixing section as well as for the temperature-controlled reaction channels allows heat transfer coefficients of up to 2,000 Wm K . The synthesis has demonstrated the potential for faster development, particularly in the preparation of relevant quantities for development studies, such as clinical trials, using the microreaction systems. 

Figure 1.8 Parallel microreactor system (the so-called CYTOS Pilot System) designed and commissioned by CPC for Clariant in 2001, for the manufacturing of diazo pigments. Source Reprinted from Ref [50], Copyright (2007), with permission from Elsevier.

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