High Resolution H NMR

Direct Observation of Free-radical 6.2 High-resolution H-NMR ... 

We have recently applied high-resolution H-NMR spectroscopy to demonstrate the oxidative consumption of salivary pyruvate by this product (Fig. 1.6), a reaction consistent with Equation 1.11 (Lynch et al., unpublished data). 

The applications of high-resolution H-NMR spectroscopy to the analysis of products arising from the lipid peroxidation process are described in Section 7. 

High-resolution H-NMR analysis has recently been employed to ascertain the nature and levels of aldehydes arising from the peroxidation of PUFAs. Indeed, chemical shifts, coupling patterns and coupling constants of the aldehydic (-CHO) and, for a,0-unsaturated... 

High resolution H NMR spectra are obtained by using a radio frequency higher than that used for low resolution spectra (typically around 300-500 MHz compared with 90-200 MHz). This results in more detailed spectra being produced. 

The low resolution H NMR spectrum for methyl propanoate has three peaks, showing that there are three proton environments - these are circled on the structural formula. The high resolution H NMR spectrum shows each of these peaks in more detail and we can see that they are made up of multiples of peaks, known as multiplets. 

P. A. Keifer, Influence of resin structure, tether length, and solvent upon the high-resolution H NMR spectra of solid-phase-synthesis resins, J. Org. Chem., 1996, 61, 1558 1559. 

The first objective of this work was to explore by high resolution H NMR and 13CNMR spectroscopy the detailed structures of poly(3-methyl-l-butene) and poly(4-methyl-l-pentene) obtained by cationic isomerization polymerization. 

In general, multiple pulse techniques sufficiently average the dipolar interactions, compress the chemical shift scale, but they do not affect heteronuclear dipolar interactions and the chemical shift anisotropy. A combination of both multiple pulse techniques and magic angle spinning, so-called CRAMPS (Combined Rotational And Multiple Pulse Spectroscopy) is found to yield satisfactory results in the solid state H NMR of solids 186). The limitations of all these techniques, from the analytical point of view, arises from the relatively small chemical shift range (about 10 ppm) as compared with some other frequently studied nuclei. However, high resolution H NMR of solids is useful in studies of molecular dynamics. 

Fig. 44. High-resolution H NMR spectra with MAS and WHH-4 sequence of 88% NH -exchanged zeolite NH4-Na-Y at various activation conditions quoted as temperature (400, 450, and 500°C) and deep bed (DB) or shallow bed (SB) (170).

There is just a handful of papers in which hydroxyl groups of silica gel are studied directly by high-resolution H NMR techniques (385-387). In particular, Hunger et al. (387) were able to observe two spectral lines in the H MAS NMR spectrum of amorphous silica-alumina gels of different composition The line at 2 ppm from TMS was attributed to nonacidic hydroxyls, since it also occurs in silica and alumina the line at 7 ppm, the... 

Nuclear magnetic resonance (NMR) has been used to study segmental motions in block copolymer solutions. The mobility of protons in polymer chains in dilute solutions has been probed using high-resolution H NMR. Association of chains into micelles leads to a reduction in mobility in the core, which leads to a broadening of the respective NMR lines that has been studied for a number of systems, as described by Tuzar and Kratochvil (1993). The sol-gel transition in concentrated solutions has been located via ]H transverse relaxation time experiments, as outlined in Chapter 4. 

A related approach for recording high-resolution H NMR spectra of solids is to use a fully deuterated sample. In this case, the residual impurity H nuclei are detected, but because these nuclei are spatially dilute, homonuclear dipole-... 

The use of high-resolution H-NMR (300 MHz) was the most useful method of solving the early confusion )... 

Boyle-Roden E, Hoefer N, Dey KK, Grandinetti PJ, and Caffrey M. High resolution H NMR of a lipid cubic phase using 52. a solution NMR probe. J. Magn. Reson. 2007 189 13-19. 

The different methods - potentiometry conductometry turbidimetry vis-cometry " calorimetry , kinetira, sedimentation , dynamic flow birefringence, light scattering , high resolution H-NMR spectrometry , chromatography, spectroscopy , electron microscopy , and others have been used for the investigation of the formation and composition of polymer-polymer complex. ... 

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