Continuous Flow Enzymatic Kinect Resolution of Benzylic Alcohols: Development of a Low-Cost Homemade Bioreactor

The continuous-flow process represents an attractive trend applied in organic synthesis and when combined with enzymatic kinetic resolution is an effective methodology to achieve enantiomeric pure compounds.1 In this work, we developed a homemade continuous-flow bioreactor packed with lipase immobilized in calcium alginate beads to perform the enzymatic kinetic resolution of racemic benzylic alcohols. The bioreactor was build using low-cost materials such as falcon centrifuge tubes, peristaltic pump tubing and connections. A column type bioreactor (8.8 cm × 1.6 cm) with 12,5 mL of total volume and 4,4 mL of working volume, equipped with an external system of thermostatic water operated in an up-flow mode (PFTR). Reaction conditions parameters such as: i) organic reactions (hydrolysis or esterification), ii) enzymes, iii) solvents (aqueous, buffer and organic solvents), iv) temperature and v) substrate were evaluated. The best result corresponds to the hydrolysis of (rac)-1-phenylethyl acetate catalyzed by the lipase from Burkholderia cepacia (immobilized in 1,0 mm alginate beads) in water at 40 °C, which reached the best conversion (42%), enantiomeric excess (> 99%) and volumetric productivity of 0.17 mmol L-1 min-1, during a three-days period of operation.