In-Line NMR Diagnostics of Hydroformylation Provided by the Segmented-Flow Microfluidic Regime

Hydroformylation is an industrial method for the conversion of olefins to aldehydes, which are further transformed to other valuable products, including primary alcohols. In industry, it is catalyzed by Rh and Co complexes, mostly under homogeneous catalysis conditions and in batch mode. The microfluidic regime offers improved mass and heat transfer efficiency due to a large gas-liquid interfacial area in the segmented-flow regime that accelerates conversion and shows increased yields of the products. However, the existing in situ spectroscopic characterization methods either lack sensitivity or require complex preparation steps to separate signals from olefin isomers, aldehydes, and other products formed in the reaction mixture. We employed ¹H NMR spectroscopy for fast in-line monitoring of hydroformylation products directly within the segmented flow. This approach avoids the replacement of organic solvents by expensive deuterated analogues as well as sample probing and preparation for ex situ NMR spectroscopy. Our work opens wide perspectives for screening and optimization of hydroformylation under microfluidic conditions.