Mechanistic investigation of homogeneously catalyzed processes often relies on the observation of the catalyst during the reaction. Knowledge of catalyst speciation, in conjunction with rate data, substrate selectivity, and potential byproduct formation, enables both optimization of catalyzed reactions, and facilitates further improvement when designing new catalysts. NMR spectroscopy is a powerful technique that has been utilized extensively for these types of investigations. However, many homogeneously catalyzed reactions that utilize gases as reagents, such as hydroformylation, hydrogenation, or ethenolysis, are not amenable to observation by NMR spectroscopy under optimized reaction conditions. We have developed a high-throughput, high-pressure NMR reactor capable of circulating gases through solution, injection of substrates mid-reaction, with direct observation of NMR-active nuceli during catalyzed reactions. Use of the HPNMR reactor is demonstrated by monitoring Rh-catalyzed asymmetric hydroformylation at a variety of temperatures and syngas pressures.

Development and implementation of high-pressure NMR spectroscopy for study of gas-containing catalytic reactions

253rd National Meeting (2017)

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