NMR Spectroscopy Methods

G.F. Ghesti, J. Lemos de Macedo, I.S. Resck, J.A. Dias and S.C.L. Dias, ET-Raman spectroscopy quantification of biodiesel in a progressive soybean oil transesterification reaction and its correlation with H NMR spectroscopy methods, Energ. Fuel, 21, 2475-2480 (2007). 

McFarlane, W. (1987). Special experimental techniques in phosphorus NMR spectroscopy. Methods in Stereochemical Anal., 8 (Phosphorus-31 NMR Spectrosc. Stereochem. Anal.), 115-150. 

Breitmaier E and Voelter W, "13C NMR Spectroscopy - Methods and Applications in Organic Chemistry", Verlag Chemie, Weinheim, 1978. 

It has been shown by gel permeation chromatography (GPC) and NMR methods that cyclolinear structure of the backbone of synthesized polymers is obtained at the interaction of dichlororgano-cyclosiloxanea and dioxy-derivatives in the presence of HC1 acceptors only. The conclusion about cyclolinear structure of synthesized polymers is based on the data of hydrodynamic studies, MMD values and results of equilibrium rigidity determination. Cyclolinear structure of the backbone is also proved by NMR-spectroscopy method on 29Si nuclei. 

Detection of thermotropic mesophase presence in PMCS-4 has induced different opinion on poly-organocyclosiloxanes), because heretofore poly(dimethylsiloxane) had been considered one of the most flexible-chain polymers. More thorough study of the spatial structure of PMCS-4, performed by 29Si NMR spectroscopy method, has shown that HFC... 

Kern D, Eisenmesser EZ, Wolf-Watz M. Enzyme dynamics dur- 130. ing catalysis measured by NMR spectroscopy. Methods Enzymol. 2005 394 507-524. 

The UV, IR and NMR spectroscopy methods were used to investigate the tautomeric equilibrium of the benzoylhydrazones 38 in solvents having different polarity. Compounds 38 exhibited 1,3-, 1,7- and 1,9-pro to tropic shifts. The fraction of azophenols 38a increased on increasing the solvent polarity and the redox potential of the quinoid form. These compounds can exist as the three tautomeric structures 38a-c. It was shown that the azo form (38a) is absent when the substituents R and R are isopropyl or tert-butyl, i.e. the keto forms are relatively stabilized by the presence of bulky ort/zo-substituents. ... 

Investigation of the system NasAlFe-Fe Oj, (Fe Oj, = Fe203, FeO) using high temperature NMR spectroscopy method was performed quite recently by Simko (2004). High-temperature NMR spectra of Al and Na chemical shifts were obtained at 1020°C. 

D.L. Rabenstein (University of California, Riverside) is investigating the biological chemistry of selenium compounds in intact erythrocytes to characterize transport across the erythrocyte membrane and their intracellular metabolism. Reactions will be characterized in erythrocytes, plasma, and aqueous solution by nuclear magnetic resonance (NMR) spectroscopy. Methods will be developed for the determination of selenols, diselenides, and selenosulfides in biological fluids and erythrocytes by high performance liquid chromatography (HPLC) and electrochemical detection. The HPLC methods will be used to determine metabolites formed at trace levels. 

New acrylate and methacrylate monomer derivatives (meth) acrylate guanidines, methacryloyl guanidine and it s hydrochloride and also a number of model (meth) acrylate compounds (corresponding acids, salts and amides, methacryloyl chloride, methylmethacrylate, guanidine and it s hydrochloride) were investigated by NMR spectroscopy method. Structure of synthesized monomers was determined, and dependence of spectral characteristics on structure of investigated compounds and used solvent was shown. 

Breitmaier, E., and Voelter, W. (1974). 3C NMR Spectroscopy, Methods and Applications , Verlag Chemie GmbH, Weinheim. 

For biomarker identification, it is also possible to separate out substances of interest from a complex biofluid sample using techniques such as solid phase extraction or HPLC. For metabolite identification, directly coupled chromatography-NMR spectroscopy methods can be used. The most powerful of these hyphenated approaches is HPLC-NMR-MS [24] in which the eluting HPLC peak is split with parallel analysis by directly coupled NMR and MS techniques. This can be operated in on-flow, stopped-flow, and loop-storage modes and thus can provide the full array of NMR and MS-based molecular identification tools. These include MS-MS for identification of fragment ions and FT-MS or TOF-MS for accurate mass measurement and hence derivation of molecular empirical formulae. 

Chodorowski, S., Leboda, R., Brei, V.V., Khomenko, K.N. and Turov, V.V. 1998. The water adsorption on silicate surface studied by H NMR spectroscopy method. In Rozwadowski, M. (Ed.) Proceedings of the Third Polish-German Zeolite Colloquium. Nicolaus Copernicus University Press. Torun, pp. 63-73. 

Gorbyk, S.P, Turov, V.V., and Chuiko, A.A. Study of interface interactions in the system cells/water/sUica by H NMR spectroscopy method. 2003. Phys. Chem. Technol. Surf. 9 123-127 (in Russian). 

Turov, V.V., BogiUo, V.I., and Utlenko, E.V. 1994a. Study of water, benzene and acetonitrile interaction with carbon black by NMR spectroscopy method. Zh. Prikl. Spektros. 61 106-113. 

Turov, V.V. and Leboda, R. 1999. Application of H NMR spectroscopy method for determination of characteristics of thin layers of water adsorbed on the surface of dispersed and porous adsorbents. Adv. Colloid Interface Sci. 79 173-211. 

The A1 mas and MQ MAS NMR spectroscopy methods were used to study the A1 coordination in the parent H-mordenite and dealuminated sanqile [05C1]. The parent H-mordenite displayed signals at 55 and 0 ppm corresponding to framework tetrahedral and octahedral coordinated A1 species, respectively. The sample calcinated at 923 K depicts additionally a shoitlder at <5 = 30 ppm, attributed to a combination of both distorted [4]ai (WaID) and Al. In the ammoniirm-treated sample calcinated at 923 K most of the peak at S= 0 ppm was removed, but the shoulder at <5= 30 ppm remained. There are present both and Al species. The sample calcinated at 923 K and treated in autoclave in a anunoniiun-water solution evidenced one peak at 55 ppm and a shoitlder at 30 ppm corresponding to " Al and " AID, respectively. When dealuminated zeohtes were treated at 353 K in basic solutions, a combined dissolution and realumination phenomenon could occur [89K2, 05C1]. The calcination at 673 K of the ammonium-water-treated sample renders a tine at S = 0 ppm and a shorrlder at 30 ppm In the MQ MAS spectrum, besides " A1, " AID, and A1 species, traces of A1 were detected -Fig. 35a,b,d. The ammonium-water thermal treatment transformed almost all penta- and octahedral A1 into... 

Improvement of the methods for isolating and separating secondary plant metabolites did not cause disruptive changes in the pace of development of the chemistry of natural compounds in the reviewed period. Fundamental changes did occur in the methodology for identifying compounds as a result of the widespread implementation of physical research methods, especially one- and two-dimensional modem NMR spectroscopy methods. This led to the obsolescence of labor- and costintensive organic chemistry methods in the area of natural products chemistry. 

Kinetics of the aralkyl hydroperoxides decomposition in the presence of tetraethylammonium bromide (Et NBr) has been investigated. Et NBr has been shown to reveal the catalytic properties in this reaction. The use of Et- NBr leads to the decrease up to 40 kJmol of the hydroperoxides decomposition activation energy. The complex formation between hydroperoxides and Et NBr has been shown by the kinetic and H NMR spectroscopy methods. Thermod5aiamic parameters of the complex formation and kinetic parameters of complex-bonded hydroperoxides have been estimated. The model of the reactive hydroperoxide - catalyst complex structure has been proposed. Complex formation is accompanied with hydroperoxide chemical activation. 

R 549 M. Zeeb and J. Balbach, Protein Folding Studied by Real-Time NMR Spectroscopy , Methods, 2004,34,65... 

In principle, these two approaches are expected to lead to end polymers I and II of identical composition and structure. The synthesized polymers were examined using GPC, DSC and NMR-spectroscopy methods. A comparative analysis of the data obtained has shown the second approach to be preferable over the first for the reason that it allows preparation of higher molecular polymers with a rather narrow molecular-weight distribution. 

By the NMR spectroscopy method [40] it is established that the >C=C< double bond in the main chain of macromolecules is more active at 1,2 PB catal54ic hydrochlorination. Its interaction with HCl results in the formation of the structure (a) (Scheme 4). At hydrochlorination of double bonds in the side chain the chlorine atom addition is controlled by formation of the most stable carbocation at the intermediate stage. This results in the structure (b) with the chlorine atom at carbon p-atom of the vinyl group (Scheme 4) ... 

By the NMR spectroscopy methods it is established that in the presence of copper (I) (II) compounds, double bonds both of the main chain and in the side units of syndiotactic 1,2-PB macromolecules are subjected to cyclopropanation whereas at rhodium acetate Rh2(OAc) mostly the >C=C< bonds in the 1,4-addition units undergo it [51],... 

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