Nitrogen and Oxygen NMR Spectra

Some nitrogen chemical shifts relating to azines are given in Table 16. [Pg.33]

Compound Solvent N- shifth 14N bandwidth at half height (Hz) [Pg.34]

1 i4N data from (B-73MI20100) 15N data from (80HCA504). b Screening constants, ppm upheld from MeN02. [Pg.34]

1 No entry in this column means data are from 15N spectra. d (85LA1732, 86JCS(PI)I249, 88JCS(PI)1509). [Pg.34]

NMR longitudinal relaxation times can be used for determination of the site of protonation in polyfunctional acids and bases (93JCS(P2)283). Thus, the 14N NMR spectrum of 4-aminopyridine shows clearly from the sharpening of the signal for the ring nitrogen that protonation has occurred here. This procedure is an important innovation in the elucidation of heterocyclic tautomeric structures, especially for the cases of fast exchange. [Pg.34]

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