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Lipases show good activity and, in some cases, improved enantioselectivity when employed in pure ionic liquids for dynamic kinetic resolution of 1-phenylethanol by transesterification.

Understanding the behavior of ionic liquids on the molecular level is essential for explaining solubilizing or reaction processes, including catalytic reactions in ionic liquids or with ionic liquids as co-solvent. Using mass spectrometry techniques it is possible to characterize their aggregate formation behavior, which depends on the used solvent. With increasing polarity of the solvent and decreasing ionic liquid concentration, the size of the formed aggregates decreases. From conductivity measurement curves "critical aggregate concentrations" were calculated, which confirm the results of mass spectrometry measurements. Addition of ionic liquids increases the solubility of acetophenone in water. This effect can be explained by the aggregate formation ability of ionic liquids. The findings can be used to explain the outstanding solubility and solvation properties of ionic liquids.

The ionic liquid (IL) Ammoeng110 contains cations with oligoethyleneglycol units and was found to be highly effective for the formation of aqueous two-phase systems (ATPS) that can be used for the biocompatible purification of active enzymes. Above critical concentrations of the IL and an inorganic salt in aqueous solution, phase separation takes place resulting in the formation of an IL-enriched upper and a salt-enriched lower phase. For the optimization of the composition of IL-based ATPS with regard to the extraction of catalytically active enzymes, the Box-Wilson method of experimental design was successfully applied; IL-based ATPS proved to be suitable for the purification and stabilization of two different alcohol dehydrogenases (from Lactobacillus brevis and a thermophilic bacterium). Both enzymes were enriched in the IL-containing upper phase resulting in an increase of specific activity by a factor of 2 and 4 respectively. Furthermore, the presence of IL within the system provided the opportunity to combine the extraction process with the performance of enzyme-catalyzed reactions. The IL was found to exhibit a stability improving effect on both enzymes and a solubility enhancing effect on hydrophobic substrates. Thus the conversion and volumetric productivity of ADH catalyzed reduction of acetophenone could be increased significantly.

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The use of ionic liquids as alternative solvents for enzyme catalysis was investigated. β-Galactosidase from Bacillus circulans catalyses the synthesis of N-acetyllactosamine starting from lactose and N-acetylglucosamine in a transglycoslyation reaction. The addition of 25% v/v of 1,3-di-methyl-imidazol-methyl sulfate [MMIM] [MeSO4] as a water-miscible ionic liquid suppresses the secondary hydrolysis of the formed product, resulting in doubling the yield to almost 60%. The enzyme can be reused several times after ultrafiltration of the reaction mixture without loss of activity. Results of different amounts of ionic liquids in the reaction medium on the thermostability of the galactosidase as well as on oxidoreductases are presented as well.

(5) show that 5 can be efficiently retained in a membrane reactor system. The X-ray crystal structure of the Ni(III) complex [NiCl 2 (C 6 H 2 {CH 2 NMe 2 } 2 -2,6-SiMe 3 -4)] (16), obtained from the reaction of 2 with CCl 4 , is also reported.

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