NMR-spectrum analysis

NMR and NMR were obtained from a 300 MHz Brucker fourier transform spectrometer. The solutions (20% w/w) were prepared by dissolving the chlorinated rubber (CR) in CDCI3 and QDg for the NMR spectra analysis with tetramethylsilane as an internal standard. 

Several spectroscopic techniques, namely, Ultraviolet-Visible Spectroscopy (UV-Vis), Infrared (IR), Nuclear Magnetic Resonance (NMR), etc., have been used for understanding the mechanism of solvent-extraction processes and identification of extracted species. Berthon et al. reviewed the use of NMR techniques in solvent-extraction studies for monoamides, malonamides, picolinamides, and TBP (116, 117). NMR spectroscopy was used as a tool to identify the structural parameters that control selectivity and efficiency of extraction of metal ions. 13C NMR relaxation-time data were used to determine the distances between the carbon atoms of the monoamide ligands and the actinides centers. The II, 2H, and 13C NMR spectra analysis of the solvent organic phases indicated malonamide dimer formation at low concentrations. However, at higher ligand concentrations, micelle formation was observed. NMR studies were also used to understand nitric acid extraction mechanisms. Before obtaining conformational information from 13C relaxation times, the stoichiometries of the... 

Lanthanide complexes [Ln(D02A)(H20) ]+ of the potentially hexadentate D02A have been studied by measuring the lanthanide-induced shifts in the O-NMR spectra. Analysis of the contact contribution indicates a decrease in the hydration number from = 3 (Ln = Ce-Eu) to n = 2 (Ln = Tb-Lu). Study of the Dq transition in the UV-visible spectra of the Eu complex... 

Compound (98) showed a molecular formula of C90H122O12, according with its FAB-MS and 13C-NMR spectra. Analysis of the data obtained from the H-NMR spectrum and the 2D NMR experiments, showed that (98) was an isomer of (97), with different substitution of the subunits. Its absolute configuration was determined by its CD curve. The lingkages between the units were determined to be C3-0-C2 , C4-0-C3 and C6 -0-C2 , C7 -0-C3 , respectively. According to the data obtained, the structure of (98) is showed below, and the compound was called triscutin B, Fig. (54). 

R 425 Y. Hatanaka, Unusual Behavior of Silicon Oligomers and Polymers Having Functional Groups , J. Organomet. Chem., 2003,685, 207 R 426 T. F. Havel, Metric Matrix Embedding in Protein Structure Calculations, NMR Spectra Analysis, and Relaxation Theory , Magn. Reson. Chem., 2003,41(Spec. Issue), S37... 

From the NMR spectra analysis it is seen that the polymer functionalization is held through the P-atom of carbon vinyl groups [17]. 

Refered to the weight of the monomeric unit. From the NMR spectra analysis. 

NMR spectra analysis suggested that the triazole byproduct, formed by click side reaction and terminating the polymerization, was not present. The triazole ring underwent a highly selective ring-opening reaction to produce the reactive ketenimine and eventually form polyimidates. 

Banwell C N and Primas H 1963 On the analysis of high-resolution nuclear magnetic resonance spectra. I. Methods of calculating NMR spectra Mol. Phys. 6 225-56... 

For both copolymers and stereoregular polymers, experimental methods for characterizing the products often involve spectroscopy. We shall see that nuclear magnetic resonance (NMR) spectra are particularly well suited for the study of tacticity. This method is also used for the analysis of copolymers. 

Fox and Schneckof carried out the free-radical polymerization of methyl methacrylate between -40 and 250 C. By analysis of the a-methyl peaks in the NMR spectra of the products, they determined the following values of a, the probability of an isotactic placement in the products prepared at the different temperatures ... 

Analysis. The infrared (ii), ultraviolet M, and nuclear magnetic resonance (nmr) spectra are distinct and characteristic for benzene and are widely used in analysis (78—80). Benzene also produces diagnostic ions in the mass spectmm (81,82) (see Analytical methods). 

The NMR spectra of cinnoline and its derivatives are complex. The unequivocal assignments are based on the complete iterative analysis of the spectra of a large number... 

Dioxolane also pseudorotates essentially freely in the vapor phase. 2,2 -Bi-l,3-dioxolane (128) has been shown by X-ray crystallography to have a conformation midway between the half-chair and envelope forms. The related compound 2-oxo-l 3-dioxolane (129) shows a half-chair conformation. This result is confirmed by microwave spectroscopy and by NMR data. Analysis of the AA BB NMR spectra of the ring hydrogen atoms in some 1,3-dioxolane lerivatives is in agreement with a puckered ring. Some 2-alkoxy-l,3-dioxolanes (130) display anti and gauche forms about the exocyclic C(2)—O bond. 

For cyclooctane, a total of 11 conformations have been suggested for consideration and their relative energies calculated. The boat-chair was calculated to be the most stable conformation. This prediction was confirmed by analysis of the temperature dependence of the F-NMR spectra of fluorocyclooctanes. The activation energy for interconversion of conformers is 5-8 kcal/mol. A few of the most stable conformations are shown below. 

The study of the NMR spectra of thiophenes has attracted considerable interest, 22,24-3sb partly because the spectra of substituted thiophenes containing only a few ring hydrogens are quite suitable for complete analysis and partly because in a series of related compounds the chemical shifts observed are related to differences in the electron distribution about chemically nonequivalent hydrogens (for review, see reference 39), especially for hydrogens far removed from the substituent. 

A detailed analysis of the NMR spectra of imidazo[4,5-c]pyridiiie (41) concluded that the IH tautomer 41a predominates (89MRC992). 

Kondo maintained his interest in this area, and with his collaborators [62] he recently made detailed investigations on the polymerization and preparation of methyl-4-vinylphenyl-sulfonium bis-(methoxycarbonyl) meth-ylide (Scheme 27) as a new kind of stable vinyl monomer containing the sulfonium ylide structure. It was prepared by heating a solution of 4-methylthiostyrene, dimethyl-diazomalonate, and /-butyl catechol in chlorobenzene at 90°C for 10 h in the presence of anhydride cupric sulfate, and Scheme 27 was polymerized by using a, a -azobisi-sobutyronitrile (AIBN) as the initiator and dimethylsulf-oxide as the solvent at 60°C. The structure of the polymer was confirmed by IR and NMR spectra and elemental analysis. In addition, this monomeric ylide was copolymerized with vinyl monomers such as methyl methacrylate (MMA) and styrene. 

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