5. 2D BC NMR reaction monitoring

Naturally, online ¹⁹ F NMR tracking is only possible in a limited number of situations where the product of interest carries a fluorine atom. Thus, in the absence of ¹⁹ F nuclei and if ¹ H spectra prove too complex to analyze, even after solvent exchange (protonated → deuterated), reaction tracking can be carried out using 2-dimensional sequences. The use of 2-D NMR experiments, where resonances are recorded on a 2-D map, makes sense at low fields thanks to a significant gain in signal separation. As such, numerous homo- and heteronuclear sequences, including ultrafast methodologies, have already been developed on low-field benchtop spectrometers as discussed in section II, although not all of these tools have yet been used for monitoring reactions conducted...