Biocatalytic Production of Catechols Using a High Pressure Tube-in-Tube Segmented Flow Microreactor

Abstract

This study reports the synthesis of 3-phenylcatechol at the preparative scale using a continuous segmented flow tube-in-tube reactor (TiTR). 2-Hydroxybiphenyl 3-monooxygenase (HbpA) was applied as a biocatalyst for the hydroxylation reaction, which is dependent on the substrate 2-hydroxybiphenyl, NADH, and oxygen. While the regeneration of the cofactor NADH was guaranteed by formate dehydrogenase (FDH), oxygen was supplied via the membrane surface from the outside of the reactor system. The oxygen transfer rate through the membrane of the TiTR was determined to be 24 μmol O2 min–1 mL–1 emphasizing the potential of the TiTR as promising technology for realizing gas-dependent enzymatic reactions. Residence time and total turnover number have been identified as key limiting parameters. It was possible to scale-up this system by extending the TiTR by additional residence time units. This allowed synthesis of 1 g of 3-phenylcatechol at a high space time yield of 14.5 g L–1 h–1.