Benchtop NMR for Catalytic Hydrogenation Reactions Suitable for Studies with Parahydrogen

Abstract Nuclear magnetic resonance (NMR) spectroscopy is an indispensable tool for analysing molecular structures and dynamics. Its applicability for reaction monitoring, especially of heterogeneously catalysed hydrogenation reactions, is limited by its low sensitivity and high cost associated with high-field NMR technology. This study describes approaches to overcome these challenges by employing a cost-effective benchtop NMR spectrometer combined with parahydrogen induced polarization (PHIP) to enhance sensitivity. The research focuses on the real-time monitoring of catalytic hydrogenations, fundamental reactions in synthetic chemistry and industrial processes. As a versatile model reaction, the hydrogenation of propene employing different catalysts is studied. The experimental setup includes a parahydrogen generator, a controllable gas flow system, and a low-field benchtop NMR spectrometer enabling in-situ and ex-situ hydrogenation experiments. Both in-situ and ex-situ experiments can be performed for monitoring gas-phase hydrogenation reactions. The setup's adaptability to different catalysts and reaction conditions, coupled with its cost efficiency, will make it accessible to a larger number of laboratories in the future.