Biocatalytic development stages

Two biocatalytic routes were also developed to the pilot stage by Ciba-Geigy, namely the enantioselective reduction of the corresponding a-keto acid with immobihzed Proteus vulgaris (route A in Scheme 12.10) and with D-LDH in a membrane reactor (route B), respechvely. It was therefore of interest to compare the four approaches. The EATOS (Environmental Assessment Tool for Organic Syntheses) program was used to compare the mass consumption (kg input of raw materials for 1 kg of product) as well as other parameters [28]. 

Attempts to resolve the racemic acid of 3 and its ester through classic resolution failed. In the early stages of development, a process based on SchoUkopf s asymmetric synthesis was developed (see Section 9.3). Large-scale development work was aimed at finding a biocatalytic process to resolve the amino acids. Racemic a,a-disubstituted a-amino esters were synthesized by standard chemistry through alkylation of the Schiff s bases formed from the amino esters (Scheme 9.5), or through formation of hydantoins. ... 

New interesting developments regarding technical processes for the preparation of AA such as biocatalytic oxidation of PA and the two-stage cleavage of oleic acid using H2O2 and O2 as oxidants are reported later in the text. However, ozonolysis coupled with an aerobic oxidative work-up of intermediates is the most important industrial process at the present time [5, 7]. 

So far, there are only a few publications that have reported the use of DESs, alone or as cosolvent, as media for biocatalytic reactions [8-14], Although only at a very early stage of development, these results have suggested that DESs deserve consideration as a potential green solvent for enzymatic processes. In this chapter, we discuss the physicochemical properties of DESs we review what has been known so far about the use of DESs as solvents or cosolvents for biocatalytic reactions and we introduce a new type of DESs, natural deep eutectic solvents (NADESs), that have an enormous potential for applications due to their nontoxicity, sustainability, and environmental friendliness. 

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