Efficient Nicotinamide Adenine Dinucleotide Phosphate [NADP(H)] Recycling in Closed‐Loop Continuous Flow Biocatalysis

Biocatalytic redox reactions regularly depend on expensive cofactors that require recycling. For continuous conversions in flow chemistry, this is often an obstacle since the cofactor is washed away. Here, we present a quasi‐stationary recycling system for nicotinamide adenine dinucleotide phosphate utilizing an immobilized alcohol dehydrogenase. Four model substrates were reduced with high enantioselectivity as a proof of concept. The two‐phase system enables continuous production as well as quick substrate changes. This setup may serve as a general cofactor regeneration module for continuous biocatalytic devices employing (co‐)substrates being miscible in organic solvent. The system resulted in space‐time yields up to 117 g L−1 h−1 and total turnover numbers for nicotinamide adenine dinucleotide phosphate higher than 12,000 mol/mol are possible.