Proton and Carbon NMR Data

In the carbon spectrum, the ortho, meta, and para carbons (hydrogen bound) are clearly seen with diminishing coupling to the CF3 fluorines, 

Similarly, the two-bond F-C coupling constants to the respective aryl carbons are all between 32 and 38 Hz. pKa data for the pentakis (trifluoromethyl)toluene, phenol and aniline are also provided in the latter scheme. 

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H and 13C NMR Data. Pertinent proton and carbon NMR data, in addition to those given above, are provided in Scheme 3.9. Again, the increase in one-bond F—C coupling constant observed in the... 

Hand13C NMR Spectra of Vicinal Difluoro Systems. Some typical examples of proton and carbon NMR data for vicinal difluoro-substituted systems are given in Scheme 3.17. 

Proton and Carbon Spectra. Proton and carbon NMR data, including 31P chemical shift and P—C coupling constants for the above compounds are given in Scheme 3.27. 

Proton and Carbon NMR Data. Some characteristic 13C and XH NMR data for fluorinated allylic alcohols and bromide are provided in Scheme 3.44. 

Proton and Carbon NMR Data. Some selected chemical shift and coupling constant data from proton and carbon spectra of chloro- and bromofluoroethylenes are presented in Scheme 3.46. 

H and 13C NMR Data. Typical proton and carbon NMR data for a,(3-unsaturated carbonyl compounds with a terminal vinylic CF2 group are given in Scheme 4.50. The pertinent F—H coupling constants have been given in the previous Scheme 4.49. Conjugation with a carbonyl group deshields the (3-CF2 carbon by 4-5 ppm. 

H and13C NMR Data. Some typical proton and carbon NMR data for trifluoromethyl ethers, sulfides, and esters are given in Scheme 5.11. Continuing the trend observed going from CH2F to CF2H to CF3 carbons, the 13C chemical shift of a trifluoromethyl ether is actually more shielded (by about 5 ppm) than that of a trifluoromethyl hydrocarbon. Scheme 5.12 summarizes the relative impact of an ether substituent upon the chemical shifts of various fluorinated carbons. 

Proton and Carbon NMR Data for Trifluoromethyl Pyridines. Little data are available, but some examples are given in Scheme 5.46. The carbon of the o-CF3 substituent is at slightly higher field than p-CF3, with the m-CF3 appearing at the lowest field, although the differences are relatively small. 

A couple of examples of other heterocycles, a pyrazole and a pyrida-zine, are given in Scheme 5.58, with their fluorine, proton, and carbon NMR data. 

The most powerful techniques of all are undoubtedly the 2-D proton-carbon experiments (Hetero-nuclear Multiple Quantum Coherence///eteronuclear Single Quantum Coherence, or HMQC/HSQC and //ctcronuclcar Multiple Bond Correlation, or HMBC) as they provide an opportunity to dovetail proton and carbon NMR data directly. 

Carbon, Proton, and Nitrogen NMR Data. Detailed proton and carbon NMR data are available for the three isomers of fluoropyridine,13 as are nitrogen data. These data are provided in Scheme 3.80. The 7H and 13C NMR spectra of 2-fluoropyridine are given in Figures 3.27 and 3.28, respectively. 

Proton and carbon NMR data for fluoroquinolines and isoquinolines are given in Scheme 3.81. 

There has been much recent interest in difluoromethyl phenyl sulfones and sulfoximines regarding their use as difluoromethylating agents. Fluorine, proton, and carbon NMR data for these compounds, along with those of analogous sulfide, sulfoxide, and sulfonic acid are provided in Scheme 4.24. No obvious trends are observed for most of the data, the exception is as the oxidation state of the sulfur increases, the CF2H carbons become shielded. 

H, 13C, and 15N NMR Data for Five-Membered Ring Systems with One Hetero Atom. Proton and carbon NMR data, although limited, are available for CF2H-substituted furans, thiophenes, benzofurans, and indoles (Scheme 4.74). 

Proton and carbon NMR data for these multi-CF3-substituted benzenes are provided in Schemes 5.53 and 5.54. Individual one-bond F-C coupling constant data are not provided because virtually all of these coupling constants are in between 272 and 276 Hz. 

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