Proton/carbon spectroscopic analysis

The catalytic system 11/MAO shows lower activity in propylene polymerization as compared to polymerization of ethylene, with a similar trend in the relationship between the polypropylene yield and Al Zr ratio (compare entries 1,2 7, and 8). The proton and carbon spectroscopic analysis of the polypropylene obtained revealed only vinyl/isopropyl end groups. The fact that... 

As active substances are separated and purified they are characterized by a combination of spectroscopic analyses and chemical correlations. Particularly useful spectroscopic analysis techniques are nuclear magnetic resonance (proton and carbon), mass spectrometry and Infra-red and ultraviolet spectrophotometry. 

Dalton TP, Li Q, Bittel D, Liang L, Andrews GK (1996) Oxidative stress activates metal-responsive transcription factor-1 binding activity. Occupancy in vivo of metal response elements in the metallothionein-I gene promoter. J Biol Chem 271 26233-26241 Danscher G, Howell G, Perez-Clausell J, Hertel N (1985) The dithizone, Timm s sulphide silver and the selenium methods demonstrate a chelatable pool of zinc in CNS. A proton activation (PIXE) analysis of carbon tetrachloride extracts from rat brains and spinal cords intravitally treated with dithizone. Histochemistry 83 419 22 Danscher G, Jensen KB, Frederickson CJ, Kemp K, Andreasen A, Juhl S, Stoltenberg M, Ravid R (1997) Increased amount of zinc in the hippocampus and amygdala of Alzheimer s diseased brains a proton-induced X-ray emission spectroscopic analysis of cryostat sections from autopsy material. J Neurosci Methods 76 53-59... 

Quahtative information on the structme of the colored corrinoids in solution can be extracted rapidly from UV/Vis and CD spectra most of the spectroscopic features can be rationalized nowadays by comparison with theoretically calculated spectra. For more precise constitutional information, some of the newly developed methods of mass spectrometry allow the analysis even of the involatile Bi2-derivatives. Modem one-and two-dimensional proton, carbon, nitrogen, and phosphoms NMR spectroscopy has proven a powerful instrument for the delineation of the stmcture of diamagnetic cobalt-corrins in solution. ESR-spectroscopy has given important information on paramagnetic corrinoid Co"-complexes, whether in frozen solutions or bound in corrinoid enzymes. X-ray adsorption fine spectroscopy (EXAFS) spectroscopy and vibrational (IR and Raman) spectroscopy are other spectroscopic techniques used more frequently now in the B12 field. 

The spectroscopic methods, NMR and mass spectrometry for predicting cetane numbers have been established from correlations of a large number of samples. The NMR of carbon 13 or proton (see Chapter 3) can be employed. In terms of ease of operation, analysis time (15 minutes), accuracy of prediction (1.4 points average deviation from the measured number), it is... 

Lycorine (1) and derivatives thereof have been the subject of a number of spectroscopic studies (42,90-92), and the proton and carbon resonances of lycorine and the a-dihydro derivative 18 have been completely assigned (90). The crystal and molecular structure of lycorine (93) and lycorine hydrobromide (94) have been established by X-ray analysis, and the structure of lycorine-chlorohydrin, which had originally been formulated as the cw-chlorohydrin 19, has been corrected and determined to be the rra/ts-chlorohydrin 20 (95). 

The study of the outer root bark of T. hypoglaucum collected in China afforded three new structures of phenolic triterpenes. Duan et al. isolated triptohypol A (80), B (81) and C (82), a series of new phenolic compounds related to celastrol [29]. Triptohypol A (80) was isolated as an amorphous powder and spectroscopic means and chemical modification determined its structure. By HREIMS the formula C30H40O6 was determined, and H-NMR spectrum showed five methyl signals, a methoxy moiety, a methylene attached to an oxygen atom and two vinyl protons. Data from 13C-NMR experiments indicated the presence of a pair of carbonyl groups and was quite similar to that of wilforol A (78). The analysis of HMQC and HMBC experiments allowed to establish the structure for rings A and B, based on the correlations observed between the proton H-l (8 6.95 ppm) and the carbons C-3, C-5 and C-10. Finally, the position of the carbonyl group was established at C-6 based on a NOESY experiment of the dimethyl derivative. 

Spectroscopic studies were performed on Ni- and Co-substituted Rds and Dx [50] while Fe replacement was done for Mossbauer analysis [35]. The Dx derivatives containing Zn and " Cd in the protein s metal site have been analy2ed by 2D-NMR spectroscopy and the solution structures have been determined [38, 39]. NMR studies were also done with the Zn, Cd and " Hg derivatives for Rd [9, 22, 51, 52]. The Ni-containing derivative is of particular interest, as Ni-substituted Rd and Dx were shown to mimic the reactivity pattern of Ni-containing hydro-genases with respect to hydrogen production, deuterium-proton and inhibition by carbon monoxide [53]. However, there is no three-dimensional structure yet available for either the Rd or the Dx Ni-substituted proteins. 

In this chapter you will employ jointly all of the spectroscopic methods we have discussed so far to solve structural problems in organic chemistry. Thirty-four problems are provided to give you practice in applying the principles learned in earlier chapters. The problems involve analysis of the mass spectrum (MS), the infrared (IR) spectrum, and proton and carbon ( H and C) NMR. Ultraviolet (UV) spectral data, if provided in the problem, appear in a tabular form rather than as a spectrum. You will notice as you proceed through this chapter that the problems use different mixes of spectral information. Thus, you may be provided with a mass spectrum, an infrared spectrum, and a proton NMR spectrum in one problem, and in another you may have available the infrared spectrum and both proton and carbon NMR. 

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