Technical-scale applications

An increasing number of examples in technical scale applications are known where nicotinamide dependent enzymes were used together with cofactor regenerating enzymes. 

Since its first report in 1989 by Schluter and coworkers [4], SPC has been developed into a powerful synthetic tool that provides access to numerous polyarylenes and related unsaturated polymers of high molar mass. Some of these polymers have gained technical-scale application, underscoring the importance and potential of the method. Key to this success has been the Suzuki-Miyaura cross-coupling... 

Other measures, such as chromium plating of the surfaces of the materials, which in experiments showed a beneficial effect in retarding the incorporation of radionuclides into the oxide layers have also been considered. As yet, however, no technical-scale application has been reported presumably, there are still technical questions to be solved. 

This chapter discusses the present status of microbial SCP production from agricultural wastes and describes some of the technical and economical problems related to the production processes that must be overcome for large-scale application to be possible. 

Kolbe electrolysis is a powerful method of generating radicals for synthetic applications. These radicals can combine to symmetrical dimers (chap 4), to unsymmetrical coupling products (chap 5), or can be added to double bonds (chap 6) (Eq. 1, path a). The reaction is performed in the laboratory and in the technical scale. Depending on the reaction conditions (electrode material, pH of the electrolyte, current density, additives) and structural parameters of the carboxylates, the intermediate radical can be further oxidized to a carbocation (Eq. 1, path b). The cation can rearrange, undergo fragmentation and subsequently solvolyse or eliminate to products. This path is frequently called non-Kolbe electrolysis. In this way radical and carbenium-ion derived products can be obtained from a wide variety of carboxylic acids. 

The third contribution presents the combination of electrochemistry and enzymatic synthesis for the selective formation of complex molecules. This quite young field of research is developing rapidly because the application of the reagent-free electrochemical procedure combined with the regio- and stereoselectivity of enzymes offers the possibility of establishing new environmentally friendly process even on a technical scale. 

Selected examples of indirect electrosynthesis which have found technical or pilot plant scale applications are discussed in the following ... 

The metal ion concentrations can be reduced from 80 ppm to less than 1 ppm with a single-pass operation. Successful applications on a technical scale are summarized in Table 16. 

An important step towards a possible application of these compounds in technical syntheses of chemicals was the successful demonstration of a ther-momorphic reversible immobihzation of perfluorinated catalysts on teflon or other solid fluorous matrices, which might be practiced in industrial low-scale applications, e.g., of pharmaceutical intermediates in the case of quantitative recovery of the organometalHc compound. The facile separation due to their physicochemical behavior and the constant good performance in coupHng reactions of the involved perfluorinated pincer complex makes this system attractive for further investigations. 

To enable an impression of the large number of possible applications of ion-exchange membranes, a brief survey is here given of the pertinent literature. The major application, which has already been implemented on a technical scale, is the electrodialytical desalting of brackish water in order to obtain drinkingwater (19, 64, 65, 66, 177, 178, 179, 180). 

This section reports selected case studies of organocatalytic reactions which have already been scaled up or which are process technology solutions with the potential for scale-up. These examples emphasize the potential of organocatalytic reactions for commercial-scale applications. The scale-up of the corresponding reactions ranges from larger lab scale applications to applications on a technical scale. The case studies discussed are ... 

Most of the substrates or products which are interesting for organic chemistry are scarcely soluble in aqueous solutions. Unfortunately, enzymes are often deactivated when used in organic solvents. Successful conversions of the hydro-phobic keto compounds thus can demonstrate general reaction principles for enzyme-catalyzed transformations of hydrophobic substrates. Various concepts concerning the application of enzymes for the transformation of hydrophobic compounds have been developed, but none of them have been applied so far in technical scale. 

This study focuses firstly on the transfer of regeneration principles as they have been developed in the field of water-based electroplating and of purification options for ionic liquids as they are experienced in other fields of ionic liquid application. A number of purification procedures for fresh ionic liquids have already been tested on the laboratory scale with respect to their finishing in downstream processing. These include distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous chromatography. But little is known yet about efficiency on the technical scale. Another important aspect discussed is the recovery of ionic liquids from rinse or washing water. 

The application of carbons in catalysis is mainly as support for active phases in various reactions. Besides a wide variety of noble metal-carbon systems for hydrogenation reactions and fuel cell applications, the large-scale application in the synthesis of vinyl acetate and vinyl chloride are important technical applications... 

The procedures for the production of supported catalysts can be divided into two main groups, namely selective removal of one or more components out of usually nonporous bodies of a compound containing precursors of the support and the active componcnt(s), and application of (a precursor of) the active components) onto a separately produced support [2] Both procedures are carried out extensively on a technical scale... 

The tetrahydroborate salts of alkali metals, M[BH4] (M = Li, Na, K),1 are important because they serve as starting materials for the preparation of other boron hydrides2,3 and because they are used frequently as reducing agents.4 The lithium and sodium salts are prepared on a technical scale.5 9 The tetrahydroborate salts of the alkaline earth metals, M[BH4]2 (M = Mg, Ca, Sr, Ba), have not as yet been used extensively however, calcium bis[tetrahydroborate(l-)], Ca(BH4)2,10 is very soluble in tetrahydrofuran (THF) and it therefore has considerable potential application as a substitute for the lithium and sodium salts. 

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