Analysis of H NMR Spectra

From a comparative analysis of H NMR spectra of structurally similar pairs of nitroxyl radicals of 3-imidazoline and 3-imidazoline-3-oxide, it was concluded that the nitrone group contributes to a more efficient long-range spin density delocalization in the conjugated n -system of functional groups bonded with atom C-4 (404). 

Established by quantitative analysis of H NMR spectra of crude product. 

In the analysis of H-NMR spectra of compounds elaborated from aliphatic fatty acids and polyamines it is rather difficult to determine the linear or branched nature of the fatty acid. In order to differentiate, well-known oxidative degradation reactions (e.g., HN03) are recommended in addition to spectroscopic methods. 

J.M. Carcellar, R Pascual, J.M. Howells, S.L. Mazucco, R. Griffiths, J.R. Pattern Recognition Analysis of H NMR Spectra from Perchloric Acid Extracts of Human Brain Tumour Biopsies, Magn. Res. Med. 39, 869-877 (1998). 

It has been found through X-ray, neutron diffraction, and electron scattering analyses that iV-sulfinylamines, -anilines, -hydrazines, and -sulfonamides have the (Z)-3 configuration in the solid state. = The structure of iV-sulfinyl compounds in solution is known with less certainty. It has been reported that a series of aryl-substituted iV-sulfinylanilines exist solely as the Z geometric isomers in solution based on analysis of H-NMR spectra and dipole moments. However, microwave spectroscopy and C-NMR spectroscopy indicate that an E/Z equilibrium exists for some AT-sulfinylamines in solution. - ... 

The complete analysis of H-NMR spectra of a series of N - and 3-substi-tuted pyridine N-imines has been reported.129 The chemical shifts (5) of the ring protons for pyridine N-imines decrease in the order H-2 (H-6) > H-4 > H-3 (H-5). A similar relationship is seen in the13C-NMR spectrum of pyridine Af-benzoylimine which indicates significant downfield shifts of C-2 (143.1 ppm) and C-4 (137.8 ppm) relative to C-3 (129.4 ppm), reflecting the electron density at these positions.130... 

The copolymerization of TXN and St was analysed in a number of papers 150,151 in terms of conventional reactivity ratios without paying attention to the proper characterization of copolymers and other factors discussed in this volume (cf. Chap. 15). Some additional information comes from the studies of similar systems, i.e. DXL-St copolymerization 152). Also in this case product characterization mainly involved solubility studies, although Yamashita et al. claimed that 1H-NMR spectra confirmed that the product is indeed a true copolymer. This claim was based on a rather limited analysis of H-NMR spectra, however, and was not confirmed by analysis of spectra of related models. Copolymerization conditions were as follows [DXL]0 = 0.7 - 3.7 mol l [St]0 = 4.5 — 2.7 mol l-1, [BF3 OEt2] = 2,5 10-2 mol 1 1, 25 °C, in toluene. After 2-8hrs, from 2% to 9% product with fr ] = 0.12 — 0.32 dl g-1 (viscosity determination conditions not specified) was obtained. 

Assfalg et al have determined the solution structure of fully oxidized mutant form of cytochrome c , which is paramagnetic with three paramagnetic centers. The assignment strategy and the algorithm of an automated program used in the analysis of H NMR spectra are described. 

In their analysis of H-NMR spectra of various end-functionalised PIB, Jiaoshi and Kennedy [50] covered inductive effects (due to ert-chlorine-ended polyisobutylenes), magnetically anisotropic effects (dne to olefin gronps and phenyl rings) and allylic coupling (dne to olefinic end groups) ... 

An independent investigation of the metabolites of American Diplophyllum albicans and D. taxifolium resulted in isolation of diplophyllin (355), a double bond isomer of (356), and 9a-acetoxydiplophyllin (361) 281). The stereostructure of (355) was based on spectroscopic evidence ( H-NMR and CD) and synthesis of ewNdiplophyllin (397) from isoalantolactone (396) by the acid-catalyzed reaction shown in Scheme 47. -diplophyllolide (398) was also obtained 281). The attachment of the acetoxyl group of (360), whose CD curve was quite similar to that of (355) to C-9 was suggested by a doublet at 5.04 ppm (/=9.7) and a doublet of doublets at 4.35 ppm (7=8.4, 10) due to the lactone methine. The stereochemistry at C-9 was based on analysis of H-NMR spectra of (360) and its dihydro- and tetrahydro derivatives, and on comparison of the spectral properties with those of (355) and related lactones. 

Co-cyclotetramerization in 1,2,4-trichlorobenzene at higher temperature (TFPN 182 ratio 20 1, 216 °C, 30 min) [100] affords mainly [ClBSubPcFij] 176 (51 %) while < 1 % of dimers 183 were isolated. As was concluded from analysis of H NMR spectra [103] the dimer 183 exists in two topoisomeric forms - syn-and a t/-isomers(or cis- and tran -isomers) which have the axial bonded ligand on one or opposite sides of the macrocyclic surface. These topoisomers were separated by column chromatography [100, 103] and their structure was established by single crystal X-ray diffraction study [100] (Fig. 9). The trimer 184 was isolated as a mixture of three possible topoisomers (syn,syn-, syn,anti- and anti,anti-) [103, 104],... 

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