Hydrogen magnetization

Laachir, A., Perrischon, V., Badri, A., Lamotte, J., Catherine, E., Lavalley, J.C., El Fallah, J., Hilaire, L., Le Normand, F., Quemere, E., Sauvion, G.N., and Touret, O. 1991. Reduction of Ce02 by hydrogen. Magnetic susceptibility and Fourier-transform infrared, ultraviolet and x-ray photoelectron spectroscopy measurements. J. Chem. Soc. Faraday Trans. 87 1601-10. 

CGU Molecule. We have made all the calculations employing the Ci symmetry group for this compound. The carbon atom is placed in the origin of coordinates. We inform the hydrogen magnetic shieldings and their polarizabilities in Table IV. The agreement between cr and values is excellent for the three employed basis sets. 

Choe BY, Suh TS, Shinn KS, Lee CW, Lee C, et al. 1996. Observation of metabolic changes in chronic schizophrenia after neuroleptic treatment by in vivo hydrogen magnetic resonance spectroscopy. Invest Radiol 31 345-352. 

Huckel s theory initiated a wealth of experimental work, all of which fitted with the prediction of enhanced stabilization in (4n + 2)7t-systems. The measure of variegated physical and chemical quantities (such as heats of combustion and hydrogenation, magnetic susceptibilities, electronic spectra and the proclivity to react in Diels-Alder reactions) was found to correlate with the extent of aromatic character, as estimated by the theoretical methods 86). 

NMR spectroscopy has shown that the allyl ligand in both platinum and rhodium allyl complexes at room temperature in deuterochloroform solution has all terminal hydrogens magnetically equivalent (20). This phenomenon may result from an interchange of the four allyl protons via a short-lived cr-allyl intermediate or transition state. As seen in Fig. 8, for such a rearrangement to take place a rotation around the C(l)-C(2) bond occurs, interchanging protons 1 and 2 concurrent with a rotation around the C(2)-C(3) bond interchanging protons 3 and 4. 

One has seen that the number of individual components in a hydrocarbon cut increases rapidly with its boiling point. It is thereby out of the question to resolve such a cut to its individual components instead of the analysis by family given by mass spectrometry, one may prefer a distribution by type of carbon. This can be done by infrared absorption spectrometry which also has other applications in the petroleum industry. Another distribution is possible which describes a cut in tei ns of a set of structural patterns using nuclear magnetic resonance of hydrogen (or carbon) this can thus describe the average molecule in the fraction under study. 

Although continuous wave NMR is sufficient for naturally abundant nuclei with strong magnetic moments such as hydrogen, fluorine and phosphorous, the study of low abundance nuclei and/or weak magnetic moments such as carbon 13 or silicon 29 requires pulse NMR. 

Nuclear magnetic resonance (NMR) spectroscopy, which tells us about the car bon skeleton and the environments of the hydrogens attached to it Infrared (IR) spectroscopy, which reveals the presence or absence of key func tional groups... 

FIGURE 13 6 The induced magnetic field of the elec trons in the carbon-hydrogen bond opposes the external magnetic field The resulting magnetic field ex perienced by the proton and the carbon is slightly less than Xr,... 

Acetylenic hydrogens are unusual in that they are more shielded than we would expect for protons bonded to sp hybridized carbon This is because the rr electrons circulate around the triple bond not along it (Figure 13 9a) Therefore the induced magnetic field is parallel to the long axis of the triple bond and shields the acetylenic proton (Figure 13 9b) Acetylenic protons typically have chemical shifts near 8 2 5... 

Proton chemical shift data from nuclear magnetic resonance has historically not been very informative because the methylene groups in the hydrocarbon chain are not easily differentiated. However, this can be turned to advantage if a polar group is present on the side chain causing the shift of adjacent hydrogens downfteld. High resolution C-nmr has been able to determine position and stereochemistry of double bonds in the fatty acid chain (62). Broad band nmr has also been shown useful for determination of soHd fat content. 

Nuclear magnetic resonance (nmr) is a nondestmctive means of measuring the amount of hydrogen in various materials for example, nmr has been used to determine the hydrogen content of coals (251). 

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