Lipase B from Candida antarctica Immobilized on Epoxy-functionalized Hollow Silica Microspheres: Efficient Biocatalysts for Enantiomer Selective Acylation of Alcohols and Amines
Hollow silica microspheres with promising physical properties (MAT540TM) as support for enzyme immobilization and biocatalyst were investigated in this study. The amine-functionalized MAT540TM was activated by six bisepoxides inclosing different spacers and used as epoxy-functionalized carrier for immobilization of lipase B from Candida antarctica (CaLB). The novel, covalently fixed CaLB biocatalysts were compared in kinetic resolution (KR) of racemic 1-phenyethanol rac-1 and five racemic amines rac-3a-e using shaken flasks and continuous-flow packed-bed microreactors. Mechanic stability, re-usability and the effect of temperature (0–90 °C) on productivity and enantiomer selectivity of the covalently immobilized CaLB were investigated. The best performing CaLB biocatalyst showed good mechanic stability after 24 h operation time in continuous-flow mode at 60 °C and provided in KRs of racemic 1-phenyethanol rac-1 with vinyl acetate and of five racemic amines with isopropyl 2-ethoxyacetate as acylating agent the non-reacted (S)-alcohol [(S)-1] or (S)-amines [(S)-3a-e] and the forming (R)-ester [(R)-2] or (R)-amide [(R)-4a-e] in good yields with high enantiomeric excess (ee > 99 %, for all).