Fast 2D NMR for Reaction and Process Monitoring

Abstract

Real-time monitoring methods are essential to the understanding and control of chemical reactions. NMR spectroscopy is particularly well suited for this purpose. It can provide quantitative information and offers great versatility in the analytical setup, making it possible to monitor reactions in chemically relevant conditions and to access sub-second timescales. 2D NMR experiments can play a crucial role in cases of peak overlap in the spectra or when structural information is sought for species transiently formed during the reaction. However, in their conventional form, 2D experiments typically require several minutes or more to acquire a full data set. In this chapter, we show how fast 2D NMR methods make it possible to push the limits of what can be monitored with NMR spectroscopy. First, we describe the motivation to use fast 2D NMR methods for reaction monitoring. Several methods for fast 2D NMR experiments have been exploited for reaction monitoring, in particular non-uniform sampling (NUS) and ultrafast 2D NMR. We also describe and compare the key features of experimental setups for reaction monitoring, such as benchtop spectrometers, flow-NMR setups, and fast-mixing apparatus. We then discuss applications in chemical synthesis and catalysis, which illustrate the potential of fast 2D NMR methods.