4. Reaction monitoring by BC 19F NMR

When ¹ H spectra of complex reaction crudes become impossible to analyze due to superposition of the signals of interest, the use of ¹⁹ F NMR can be a highly relevant alternative, provided, of course, that the products of interest carry a fluorine atom. In fluorine NMR, the risks of signal superposition are low due to the very large recording spectral window, classically between -300 and 100 ppm. Furthermore, recording a ¹⁹ F spectrum is fast and the natural abundance of ¹⁹ F (100%) allows a sensitivity comparable to proton NMR. The relevance of flow NMR monitoring by recording ¹⁹ F spectra was highlighted by Rehm et al. for the synthesis of fluorinated compounds...