Search

The use of immobilized alcohol dehydrogenases (ADHs) offers numerous advantages, especially in the reaction conditions required by industrial applications. Looking for more efficient and cost-effective methods of ADH immobilization, in this study we explored silica-based supports as an alternative to the use of functionalized polymeric resins. Three commercially available ADHs were immobilized by adsorption and covalent bond formation. The obtained supported biocatalysts were applied for the bioreduction of acetophenone and some derivatives with good yields and excellent enantioselectivity. The important intermediate (S)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol was obtained with a high enantiomeric excess (>99%) by using the highest performing immobilized ADH sample. The reusability of this biocatalyst was investigated in a flow system for five consecutive runs; the experiments showed that the biocatalyst could be recycled without a loss of activity and enantioselectivity. Finally, cross-linking with the glutaraldehyde of the supported biocatalyst was also carried out to prevent the leaching of the enzyme during the catalytic reactions. [ABSTRACT FROM AUTHOR]

Both enantiomers of 1‐(3,5‐bis(trifluoromethyl)phenyl)‐ethanol (BTPE) constitute important building‐blocks for the synthesis of active pharmaceuticals ingredients (APIs). The reduction of 3',5'‐bis(trifluoromethyl)acetophenone (BTAP) performed with soluble and immobilized ketoreductases (KREDs) can be considered as one of the most efficient routes to produce enantiopure BTPE. In the present work, a commercial KRED was employed as biocatalyst after undergoing immobilization processes and it proved to be extremely efficient in the asymmetric synthesis of (S)‐BTPE. The immobilization was studied on a set of different commercially available supports. The best results were obtained with samples immobilized via covalent interaction on short chain amino‐functionalized support. Two reaction parameters, temperature, and solvent were optimized in the biocatalytic reduction of BTAP in batch conditions. A 90 : 10 (v/v) 2‐propanol (IPA): water solvent system and 30 °C proved to be the best reaction conditions in terms of substrate conversion and easy recovery of the product by simple solvent evaporation. Biotransformations were then performed in a flow system under optimized reaction conditions obtaining with most samples complete conversion after 24 hours and excellent enantiomeric excess (>99.9 %). Finally, the reusability of the immobilized biocatalyst was successfully tested in five consecutive reaction cycles, demonstrating the potential of this approach. [ABSTRACT FROM AUTHOR]