Organic synthesis devices

These devices have a special function vhich allows them to perform electro-organic synthesis. Typically, they contain electrode structures to generate electrons as tunable reactants . Often, these electrodes are constructed as plate-type structures, sometimes also being the construction material for the channels themselves. 

These are total systems or even plants made for parallel automated organic synthesis, typically in the liquid phase. In this section, no commercial devices (typically not relying on micro flow processing) are considered, but rather only specialty apparatus developed in the framework of chemical micro processing. 

Mitchell, M. C., Spikmans, V., Bessoth, F., Manz, a., de Mello, A., Towards organic synthesis in microfluidic devices multicomponent reactions for the construction of compound libraries, in van den Berg, A., Olthuis, W., Bergveld,... 

Other microwave-assisted parallel processes, for example those involving solid-phase organic synthesis, are discussed in Section 7.1. In the majority of the cases described so far, domestic multimode microwave ovens were used as heating devices, without utilizing specialized reactor equipment. Since reactions in household multimode ovens are notoriously difficult to reproduce due to the lack of temperature and pressure control, pulsed irradiation, uneven electromagnetic field distribution, and the unpredictable formation of hotspots (Section 3.2), in most contemporary published methods dedicated commercially available multimode reactor systems for parallel processing are used. These multivessel rotor systems are described in detail in Section 3.4. 

Simultaneous application of UV and MW irradiation has found widespread use in industry. The techniques are based on the conventional UV lamps and MW-powered electrodeless lamps and MW devices [28], The following paragraphs discuss several patents and papers that describe industrial microwave photochemistry, such as treatment of waste water, sterilization, or industrial photo induced organic synthesis. 

After the discovery by Fischer and Maasbol of the first stable carbene complexes in 1964, i.e., [(CO)5W =C(OMe)R ] [21], generation of related metaUacumulene derivatives [M]=C(=C) =CR2 (n > 0) was obviously envisaged. Thus, it is presently well-established that stabilization of these neutral unsaturated carbenes by coordination to a transition metal center is possible by the use of the lone pair of electrons on the carbenic carbon atom, via formation of a metal-carbon a-bond (electron back-donation from the metal fragment to the carbon ligand may strengthen this bond). This has allowed the development of a rich chemistry of current intense interest due to the potential applications of the resulting metallacumulenic species in organic synthesis, as well as in the construction of molecular wires and other nanoelectronic devices [22]. 

Oligonucleotide and peptide microarrays can be prepared in situ with light-directed synthesis on a glass surface in conjunction with either a photolithographic method or using a micromirror device (2,11-15). However, these methods are not useful for most organic synthesis. Furthermore, such approaches require equipment that is not readily available. Spot synthesis on cellulose membrane is another in situ synthesis method, but the resulting microarrays are low density (16). 

Figure 3.5 Reactor for batchwise organic synthesis. 1. Reaction vessel 2, top flange 3, cold finger 4, pressure meter 5, magnetron 6, forward/reverse power meters 7, magnetron power supply 8, magnetic stirrer 9, computer 10, optic fiber thermometer 11, load matching device 12, waveguide 13, multimodal cavity (applicator). (From Ref. 712, reproduced with permission.)...

However, continuous reactors, generally fixed bed reactors, which are currently used in gas phase reactions in refining and the petrochemical industry, can also be used for liquid phase organic synthesis in the presence of zeolite catalysts. Better results in terms of catalyst stability are often obtained. However, efforts have still to be made to encourage Organic Chemists to substitute fixed bed reactors, whose setup is relatively simple, to batch reactors, which are virtually the only devices used in academic organic chemistry. 

The term reactive filtration may be used in a variety of applications. A simple search of the internet provides results such as reactive filter paper [1], adsorption filters for removing heavy metals from water [2], solid matrices used in organic synthesis [3], membranes for wastewater treatment, or even dialysis machines, filters for deep-frying pans and devices for the dechlorination of shower water by reaction with vitamin C. Most of the applications termed reactive filtration would be named heterogeneous catalysis or adsorption from a chemical engineer s point of view. 

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