CEM Corp

Similar parallel reactors as described above for the ETHOS multimode microwave reactor (Milestone, Inc.) are also available for the MARS-S multimode reactor from CEM Corp. [81]. Recently the construction of a parallel reactor with expandable reaction vessels that accommodate the pressure build-up during a microwave irradiation experiment has been reported [87]. The system was used for the parallel synthesis of a 24-membered library of substituted 4-sulfanyl-lff-imidazoles [87]. 

Additional applications of this technology for rapid lead discovery and lead optimization have been reported [87, 90-93]. It should also be noted that a variety of chemical transformations, in particular in the area of transition-metal catalyzed reactions, have been performed with this or related equipment (Chapt. 11) [25]. Other monomode microwave reactors using related concepts to introduce high-throughput were recently introduced by CEM Corp. (Discover or Explorer line of products, Fig. 12.7.) [81]. At the time of writing this review no published synthetic applications using this microwave reactor were available. 

Figure 12.7 Monomode microwave reactor Discover (without automation) for use with open or sealed vessels of different volumes (CEM Corp.) [81]. A related instrument with automation (Explorer) has recently been introduced.

Acknowledgements. The author thanks Biotage (Uppsala, Sweden), Anton Paar (Graz, Austria), and CEM Corp. (Matthews, NC, USA) for their support and for the possibility to test their microwave reactors in the kilolab. He also thanks all the colleagues and people who were involved in this project for their input and the challenging discussions. 

Figure 28-13 Extraction vessels in a microwave oven that processes up to 12 samples in under 30 min. Each 100-mL vessel has a vent tube that releases vapor if the pressure exceeds 14 bar. Vapors from the chamber are ultimately vented to a fume hood. The femperature inside each vessel can be monitored and used to control the microwave power. [Courtesy CEM Corp.. Matthews. NC.]...

Vasudevan, A., Microwave Synthesis Chemistry at the Speed of Light, Hayes, B.L., ed., CEM Corp Publishing, 2002. 

In general, organic extraction and acid digestion use different types of microwave apparatus, as these two processes require different reagents and different experimental conditions. A new commercial system, Mars X (CEM Corp., Matthews, NC) offers a duel unit that can perform both proce-... 

Digestions were carried out in a microwave (MW) sample preparation system CEM (Corp., Matthews, NC, USA) model MARS-Xpress equipped with a 1400 W magnetron with adjustable power down to 1 percent increments and operating at a... 

Figure 36-1 A moderate-pressure vessel for microwave decomposition. (Courtesy of CEM Corp., Matthews, NC.)...

The application of microwave energy to organic compounds, such as solvents, can pose serious hazards. The hazard is greater with flammable Uquids. Two main types of apparatus are available commercially. They make use of singlemode or of multi-mode technology. The readers are invited to review commercial literature from CEM Corp. [9] and Prolabo [10], currently the only two manufacturers that offer legitimate MAP instrumentation. 

Figure 1-1. A CEM Corp. model AVC-80 computer-controlled microwave oven for drying foods.

FIGURE 5.4 The CEM MARS in sealed-vessel mode. (Reproduced with permission from CEM Corp.)... 

Microwave apparatus CEM Explorer, CEM Corp, 3100 Smith Farm Road, Mathews, NC 28106-0200. 

CEM/H. F. Burcharth and S. A. Hughes, Fundamentals of design. Coastal Engineering Manual, eds. L. Vincent and Z. Demirbilek, Part VI, Design of Coastal Project Elements. Chapter Vl-5-2, Engineer Manual 1110-2-1100 (US Army Corps of Engineers,... 

CEM, Coastal Engineering Manual (US Army Corps of Engineers, Vicksburg, 2006). 

CEM, Coastal Engineering Manual, US Army Corps of Engineers, Vicksbmg (2006). CIRIA-CUR-CETMEF, The Rock Manual, CIRIA, London (2007) (also CUR/ CIRIA, Manual on use of rock in coastal engineering, CUR/CIRIA report 154, Gouda, the Netherlands, 1991). 

Cation exchange membranes. The most commonly used cation exchange membrane (CEM) is Nafion 117 (Dupont Corp., available from Ion Power, Inc.) (Fig. 5.4). The code 117 is used to distinguish the thickness of the membrane (0.019 cm) from other Nafion membrane thicknesses. This membrane was developed for use in an HFC and thus was optimized to create a stable and conductive environment for high proton concentrations (low pH) under conditions where the water content is carefully controlled. However, this material becomes completely saturated (flooded) with water in an MFC, producing a pH reflective of the solution properties (likely neutral pH). Thus, it does not function according to its intended purpose in an MFC as it cannot operate under its designed conditions. 

Kim et al. (2007b) tested three different ultrafiltration membranes (Amicon Corp.) for power generation in two different types of two-chambered MFCs. They found that these membranes had high internal resistances, and thus produced less power than the CEM or AEM membranes (Table 5.1). The 0.5 K membrane had extremely high internal resistance values. As a result, power was only 5 mW/m in two-chamber bottle reactors whereas the other membranes did not appreciably impact power generation as they all produced 33-38 mW/m. In the cube reactors, where internal resistance was lower due to a closer electrode spacing and the use of an air cathode, the 1 K membrane produced only slightly less power than the CEM membrane. Thus, in theory it may be possible to replace the CEM membrane with a more conventional ultrafiltration membrane in an MFC, but membranes must be developed that result in lower internal resistances. 

---