Online reaction monitoring by single-scan 2D NMR under flow conditions

Abstract

Single-scan 2D NMR based on spatial encoding can be used to monitor chemical reactions with a flow unit in realistic reaction conditions.

NMR-based metabolomics and fluxomics: developments and future prospects

“…One of the first papers along this direction was published by Van et al, who reported a higher performance of 2D TOCSY with zero-quantum filtering, versus 1D 1 H NMR for metabolic profiling of urine sample from mice. 40 They nicely demonstrated that statistical models obtained from 2D spectra were more efficient than those obtain from 1D data to characterize statistically relevant changes in low abundance metabolites. However, the experiment duration associated with 2D spectra was extremely long (17 hours per spectrum based on the paper's experimental parameters) and not suited to routine analysis.…”

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

“…Considering the nuclear magnetic resonance spectroscopy (NMR), the reaction monitoring using online or tube experiments could provide useful results. [26,27,28] In addition, the experimental practicability, structural characterization combined with a quantitative method, provide distinct advantages of NMR over other analytical techniques, as Infrared or Raman spectroscopies, which provide information only about the organic functional groups, and for which quantitative analysis is not a trivial task. The use of NMR experiments to follow the chemical changes that are associated with a synthetic methodology is not a new strategy.…”

Engineering aspects of FlowNMR spectroscopy setups for online analysis of solution-phase processes

“…The use of ferromagnetic materials is not recommended for FlowNMR setups, so common tubing materials are polymers which come with the additional benefits of being lightweight and flexible. 39,40,48,66,67 However, the correct choice of polymer tubing for a given application (i.e., sample composition and reaction conditions) is not trivial, and safety aspects have to be considered in addition to chemical compatibility. [68][69][70][71] Table 1 lists some key physical properties of commercially available tubing materials in comparison with austenitic stainless steel as the standard for HPLC applications.…”

“…26,27 A number of flow devices have been developed that allow a continuous stream of sample solution to be pumped through the NMR active region of the spectrometer, [28][29][30][31][32][33][34][35][36] developments that actually date back to early days of NMR spectroscopy in the 1950s. 37 Recent examples include the use of FlowNMR coupled with oxygen probes in the elucidation of the mechanism of amination reactions, 38 the development of low-volume flow system containing biological organisms within the flow tip for solution-state in vivo NMR, 39 the use of ultra-fast single scan 2D NMR in flow 40 and the real-time monitoring of oxidative wastewater treatment. 41 Whatever the application, key to obtaining NMR data relevant to the process occurring within the external vessel is an appropriately designed flow system (Fig.…”