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Although NMR offers some strategies for determining the presence of a fluorine atom(s), fragment loss of a CF3 group can be determined from a mass spectrum. The EI MS for 2,2,2-trifluoro-N,N-dimethylacetamide (Mmi = 141 Da) is shown below. The ion peak at m/z 72 indicates the loss of a CF3 group. Although the ion peak...

MS and NMR are complementary elucidation tools. Knowing when to apply the correct tool can facilitate the elucidation process. Compounds with bromine atoms exhibit a distinct ion pattern on a mass spectrum. The A+2 peak for a monobrominated compound appears at almost identical intensity to the 79Br peak due to the presence of 81Br (~49.3%...

2D NMR experiments such as 1H-13C HMQC, HSQC, and HETCOR spectra, offer the elucidator the opportunity to assess the presence of a fluorine atom(s). The 1H -13C HSQC spectrum below is another case where a protonated carbon that experiences 13C-19F coupling shows a unique correlation pattern. The CH carbon projected on the F1 domain at...

Experiments such as 1H-13C HMQC, HSQC, or HETCOR can be used to suspect the presence of fluorine but not necessarily rule out the absence of fluorine. The stipulation behind this assessment is that a carbon from either a CH, CH2 or CH3 group must experience 13C-19F coupling(s). The spectrum below is a region of an...

Without a set routine to acquire a 19F NMR spectrum for every single sample, an elucidator must resort to routine NMR experiments for clues to the presence or absence of fluorine. For the elucidator who routinely acquires a proton decoupled 13C NMR, the spectrum can provide some clues into the presence of fluorine. Carbons in...

Ideally, identifying whether a fluorine atom(s) is present is as simple as acquiring a 19F NMR. However, running ‘uncommon’ experiments is not usually my first step in an elucidation (MDE). Imagine a scenario where the elucidator is unsure whether fluorine is present. He/she acquires a 19F NMR and sees no 19F resonances. Therefore the extra...