Hydroxy reaction engineering

For L-fert-leucine [12,13] and some other amino and hydroxy acids [20,22,71], as well as for chiral alcohols [49], detailed reaction engineering studies have been performed and published in recent years [82]. The main targets were to increase tiie tin of the coenzyme involved, mainly NADH, and to decrease the product-specific catalyst consumption. Typical results are compiled in Table 5 for L-7erf-leucme as a highly soluble substrate, or product, and (5 )-l-pheny 1-2-propanol and (5)-2-octanol as poorly soluble products obtained in different types of reactors. The reactions analyzed are shown in Figs. 4 and 13, respectively. 

Low levels of cresols are constantly emitted to the atmosphere in the exhaust from motor vehicle engines using petroleum based-fuels (Hampton et al. 1982 Johnson et al. 1989 Seizinger and Dimitriades 1972). Cresols have been identified in stack emissions from municipal waste incinerators (James et al. 1984 Junk and Ford 1980) and in emissions from the incineration of vegetable materials (Liberti et al. 1983). Cresols have also been identified as a component of fly ash from coal combustion (Junk and Ford 1980). Therefore, coal- and petroleum-fueled electricity-generating facilities are likely to emit cresols to the air. The combustion of wood (Hawthorne et al. 1988, 1989) and cigarettes (Arrendale et al. 1982 Novotny et al. 1982) also emits cresols to the ambient air. Cresols are also formed in the atmosphere as a result of reactions between toluene and photochemically generated hydroxy radicals (Leone et al. 1985). 

Cassimjee et al. reported [22] that a variant engineered aminotransferase at TrpOOCys from Chromohacterium violaceum showed a 29-fold increase on spedfidty for synthesis of (S)-phenylethylamine and about fivefold on spedfidty for 4 -substituted acetophenones, where the groups at 4 position were bromo, chloro, hydroxy, methoxy, nitro, methyl, and cyano. The amine donor was isopropylamine. The reaction schemes are shown in Figure 7.5. 

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