Correlation chart, chemical shift values

FIGURE 3.20 A simplified correlation chart for proton chemical shift values. 

Most chemical shifts have 8 values between 0 and 15. A small 8 value represents a small downfield shift, and vice versa. A simplified correlation chart for proton chemical shift values is shown in Table 2 [37]. 

In the introductory course, you learned to use four basic kinds of information from NMR spectra number of signals, chemical-shift values, integrated signal area, and splitting patterns. We will now delve furtha- into some of these, particularly the splitting patterns. A brief correlation chart is provided in Table 10.7. More extensive listings can be found in the references. 

The chemical shift is used to identify functional groups and to aid in determining structural arrangements of groups. These applications arc based on empirical correlations between structure and shift. A number of correlation charts and tables " have been published, two ol which are. shown in Figure 19-17 and Table 19-2. Keep in mind that the c.Kaci values for 8 may depend t)n the nature of the solvent as scll as on the concen-... 

The following correlation charts list the chemical shifts of some fluorine-containing compounds relative to neat CFCI3. All chemical shifts are those of neat samples, and the values pertain to the fluorine present in the molecule. ... 

Over 100 SbCls affinity values are collected in Table 2.2. The sample of Lewis bases contains mainly oxygen bases and, among these, mainly carbonyl compounds. Only nine nitrogen bases (seven nitriles, one pyridine, one amine) have been studied. The scale lacks second-row bases, carbon bases and halogen bases. We have not reported the values estimated indirectly from correlations between DN and solvent basicity-dependent properties, such as nuclear magnetic resonance chemical shifts of the Na nucleus [27] or of the chloroform proton [28], These values would be valid only if there was no separation into families of bases in the correlation chart, which is rarely found. As shown in this book, family-dependent correlations between basicity-dependent properties are generally the norm. 

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