NMR Examination

Lundquist 1979b, Ralph and Young 1983, Hauteville et al. 1986, Ralph et al. 1987, Brunow et al. 1989. 

Integrals can be determined by the spectrometer or by measurements of peak areas on a recorded spectrum (Adler et al. 1987). When a peak of interest overlaps other peaks, it may be desirable to determine an upper and lower value for the peak area (Adler et al. 1987). The following methods have been employed to express the results of integrations in structural terms calculations starting from the total integral of the lignin spectrum and the amount of hydrogen/ 

2 62 Benzyhc protons in [i (S structures of secoisolariciresinol type, benzylic protons in 

4 65 H/( in (I 0-4 structures (methylene protons in cinnamyl alcohol units) 

7 41 Aromatic protons in benzaldehyde units and vinyl protons on the carbon atoms 

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Difluoromonosulfane and Difluorodisulfane Difluoride. Difluoromonosulfane [13814-25-0] (sulfur difluoride), SF2, and its dimer, disulfane tetrafluoride [27245-05-2] SF SF, are both extremely unstable compounds which have only a fleeting existence except under rigorously controlled laboratory conditions. These compounds may be prepared by passing SCl vapor over HgF2 at 150°C (131). Electronic and nmr examinations of SF2 have been reported (132,133). 

Careful spectroscopic (infrared and NMR) examination of these compounds should result in clarifying the structural assignments. 

We examined a 30-year-old male AGL-patient (BMI 15.4 kg/m, severe insulin resistance) to assess and compare findings of derived metabolic data and NMR examinations." A reduction of subcutaneous adipose tissue was... 

Quantitative NMR examination of the hydrolysis of dimethyl phosphonate (245) using 0-enriched water under base-catalysed conditions supports a mechanism involving P—O rather than C—O bond cleavage. 

During a proton NMR examination of a CCI4 solution of MejNsBgFs, an extraneous peak was observed in the spectrum, although the borazine was known to be analytically and mass spectrometrically pure. One microliter of the solution was subjected to GC/MS analysis. Peaks identified as trimethylsilane (TMS) and CCI4 were obtained followed by the expected MesNjBsFs (m/e 177, 176, etc.). An additional component... 

By VPC based on RCOR. Isolated yields are in parentheses. 100% Excess monolithiutn acetylide was used. The product was >99% 2-ethynyl-endo-2-norbornanol by VPC and NMR examination. 

It has also been shown (93) that the additions of benzonitrilio benzylide to the substituted analogues 183 and its (E) isomer were not only highly regioselective but also highly stereoselective. Thus in both cases, NMR examination of the product showed that only a single diastereoisomer (e.g., 184) was obtained. 

The existence of the covalently hydrated quinoxaline 252 discussed above was further confirmed by NMR examination of the 1-methyl-quinoxalinium cation in basic methanol-d4. This proved to be complex,... 

Reactions of unsaturated esters with electron-rich alkenes have been reported to yield only cyclobutane derivatives. However, NMR examination of the products has indicated the formation of substituted 3,4-dihydro-2H-pyrans. The most informative feature of the spectra is the C-2 proton coupling constants of ca. 3 Hz with the two different protons at... 

These findings have been confirmed by NMR analysis.284-286 Allingham and Crabb et a/.287 agreed with these conclusions on the basis of NMR examination, but they did not rule out a certain amount of form 119 existing in equilibrium with 117 due to nitrogen inversion. 

Inversion at the nitrogen atom, mentioned already,267 was also discussed by Italian,18 French,17 and Soviet authors272 on the basis of NMR examination of derivatives of tetrahydro-1,3-oxazine. In another series of papers,32-33,273 Soviet authors concluded from NMR, dipole... 

In this context, LC-NMR and LC-NMR-MS proved to be powerful tools for speeding up the process of screening fractions of biologically active natural products for novel compounds, justifying the laborious isolation and comprehensive off-line NMR examination. 

Plasticized PVC provides an example of an important, frequently studied, and nominally homogeneous material that has yet to be fully characterized. X-ray, infrared and earlier NMR examinations of PVcL3 i have been interpreted as indicating an inhomogeneous material. 

The 13C NMR examination of CBS cured SBR was performed on unfilled, silica filled, and carbon black filled samples [41], Several different SBR samples with respect to styrene content and cis, trans, and vinyl BR content were used. The unfilled SBR samples gave 3 major peaks that appeared at 51.0, 50.2, and 49.3 in a spectrum similar to BR vulcanisation. Unfortunately, peaks below 45 ppm are obscured by the different main chain structural peaks of SBR. A difference was seen in the rate of formation of these peaks in filled samples with silica inhibit the vulcanisation rate compared to carbon black filled samples. 

Barron PF, Frost PL, Doimo L, Kennedy MJ (1985) nC-CP/MAS NMR examination of some Australian hardwoods and their chemical and biochemical residues J Macromol Sci Chem A22 303-322... 

In these two species, [ Hyaline was readily incorporated Into the branch alkanes- A C-NMR examination of the incorporation of [3,4,5- C,]valine into the branched alkanes of the housefly... 

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