Regular articleAn organic-single-phase CSTR process for the chemo-enzymatic epoxidation of α-pinene enables high selectivity and productivity

•The ospCSTR enables high selectivity, catalytic productivity and space-time yield.•Operation periods up to 17 d could be performed.•Constant space-time yield was maintained over 100 h with intermittent lipase dosing.•Intermittent lipase dosing almost tripled catalytic productivity to 282 gPO g−1CalB.•Longest operation of chemo-enzymatic epoxidation reported so far.

The aim of this work was to develop a new process strategy for the in-situ lipase-mediated synthesis of α-pinene oxide. To minimize the limitation of enzyme deactivation encountered in these reaction cascades, an organic-single-phase continuous stirred tank reactor (ospCSTR) process was developed. Considering the numerous degrees of freedom of this continuous multistep reaction which due to enzyme deactivation additionally has no steady-state, the process development is a challenging task. Therefore, the influence of operating parameters on the efficiency was studied in detail. Due to the avoidance of harsh conditions, at optimized parameters α-pinene oxide was produced selectively (95%), and with high space-time yields (880 gPO L−1 d−1). The catalytic productivity (118 gPO g−1CalB) was significantly higher than previously reported. To counterbalance the reduced but still present deactivation, the opsCSTR was enhanced with intermittent enzyme dosing which, for the first time, enabled long-term operation, high catalytic productivity, and high space-time yield. With the ospCSTR augmented by enzyme dosing, we report an economical process for a chemo-enzymatic epoxidation of sensitive terpenes like e.g., α-pinene.

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