高岭石结构缺陷的 1H MAS NMR和Raman研究

The structure default of kaolinites was characterized with ¹H MAS NMR and Raman spectra. Although the HI indexes of Suzhou and Maoming kaolinite are similar, their ¹H MAS NMR and Raman spectra are very different. ¹H MAS NMR showed that the hydroxyl proton chemical shifts of Suzhou kaolinite are in the higher field and with larger different between the inner surface hydroxyls protons and inner hydroxyls proton chemical shifts than Maoming kaolinite. Raman spectra showed that the surface hydroxyls stretching vibration bands of Suzhou kaolinite are in the high frequency region, and the half height widths of the bands are 7.0～14 cm^-1. The area ratio S_z/(S_z+S_A), where S_Z and S_A are the areas of bands 3685 cm^-1 and 3695 cm^-1 respectively, is 0.23. But the surface hydroxyls stretching vibration bands of Maoming kaolinite are in the low frequency region, and the half height widths of the bands are 8.9～15.1 cm^-1. The area ratio S_z/(S_z+S_A) is 0.77. Those data proved that Suzhou kaolinite has lower structure default than Maoming kaolinite and ¹H MAS NMR and Raman spectra are effective method for study of kaolinite structure default.     

1H,2H,19F and 31P NMR and ESR investigations of aryl-t-butyl nitroxides

Aspects of translocation of spin to fluorine and phosphorus are discussed. (2p–3d)_π overlap in phosphorus is insignificant. Spin polarization and (2p–3p)_π overlap are opposing spin transfer mechanisms for phosphorus. The³¹P NMR spectrum of the nitroxide from 7a shows some features which are not fully understood. Some gain in resolution of the NMR spectra can be achieved by deuteration, but it is considerably lower than predicted.     

1H magic angle rotation NMR in polymer studies

The principles of the method of NMR line narrowing by measurement with spinning of the sample about the magic axis (MAR-NMR) are introduced, with particular emphasis on the effects of internal motion upon the possibilities and limitations of the method. The applications of the method in ¹H-NMR studies of polymer structure and dynamics are then reviewed. Due to both theoretical and experimental limitations, narrowing of dipolar broadened NMR lines by MAR can be observed in ¹H NMR spectra only in those cases where internal motion is anisotropic, or in heterogeneous systems where line width is limited by differences of magnetic susceptibility. In polymers, both solid and liquid, the method makes possible differentiation between isotropic and anisotropic internal motion. In systems with anisotropic internal motion, MAR-NMR makes possible a characterization of motional codes which normally are obscured by residual dipolar interactions, as well as of geometrical restrictions upon these motions.     

13C-{1H} NMR spectra of episulphide copolymers

Ethylene sulphide-isobutylene sulphide and propylene sulphide-isobutylene sulphide copolymers have been prepared using anionic catalysts and investigated by ¹³C-{¹H} NMR spectroscopy. The carbon-13 NMR spectra are assigned in terms of diad and triad sequences. There is discussion of the effects of mono- or dimethyl substitution in the α, β, γ or δ positions on the chemical shift of the main chain carbon atoms. It has also been shown that for isobutylene sulphide, as for propylene sulphide, under the influence of an anionic catalyst, there is a normal ring opening only at the primary carbon atom.     

NMR study (1H, 13C and 29Si) of the methylallylsilanes

¹H, ¹³C and ²⁹Si NMR data for the compounds (CH₃)_xSi(CH₂CHCH₂)_4-x are reported. The ¹H resonances from the π system are indicative of the electron-supplying inductive effect (+I) of the (CH₃SiCH₂, moiety but the corresponding ¹³C_π chemical shifts seem to be influenced by a sterically induced polarization of the C-H bonds. The ¹³C_All, ¹³C_Me and ²⁹Si chemical shift data reveal an important neighbour anisotropy contribution originating from the π system. Ultraviolet study of the compounds mentioned above gives indication of a σ—π conjugation in accordance with PES and ab initio results [1—5]. The trend observed in the various coupling constants is too small to be Interpreted.     

Structural analysis of alkylated coal by 1H and 13C NMR spectroscopy

Summary A method is presented for derivation of a series of structural parameters describing the average molecule of soluble butylated coal. It is based on ¹H and ¹³C NMR spectral data, molecular mass measurement and ultimate analysis. Average structural models of coals can be constructed in this way.

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Strukturanalyse von alkylierter Kohle mit Hilfe der ¹H- und ¹³C-NMR-Spektroskopie

Zusammenfassung Ein Verfahren wird vorgestellt zur Ableitung einer Reihe von Strukturparametern, die das Durchschnittsmolekül von löslicher butylierter Kohle beschreiben können. Es beruht auf ¹H- und ¹³C-NMR-Spektraldaten, Messungen der Molekülmasse sowie der Elementaranalyse. Durchschnittliche Strukturmodelle von Kohlen können dadurch erstellt werden.

     

A 400 mhz 1H NMR study of the eight basic heteroyohimbine alkaloids

A 400 MHz ¹H NMR study of the eight basic heteroyohimbine alkaloids has permitted the chemical shifts of all the protons to be established and most of the main coupling constants to be determined. A conformational study of the heteroyohimbine structures is presented.     

Multilayered iron complexes of metacyclophanes. 1H NMR behavior

Syntheses are described for a series of (η⁶-cyclophane)(η⁵cyclopentadienyl)iron(II) complexes, where the cyclophane moiety is anti-[2.2]metacyclophane, anti-4,12-dimethyl[2.2]metacyclophane, anti-4,12-dimethyl-7,15-dimethoxy[2.2]metacyclophane, and [2.2](2,5)thiophenophane. The triple-layered complexes η⁶,η⁶-anti-[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) and (η⁶,η⁶-anti-4,12-dimethyl[2.2]metacyclophane)bis[(η⁵-cyclopentadienyl)iron(II)] bis(hexafluorophosphate) were also prepared. The NMR spectra of these compounds provide a useful insight into the nature of the iron-cyclophane bonding.     

NMR (1H, 13C, 29Si) study of some allylhalogenosilanes

¹H, ¹³C and ²⁹Si NMR spectra of the allylchlorosilanes (CH₂CH-CH₂-)_xSiCl_4?x and of triallylbromosilane have been analysed. Results are discussed in terms of inductive and steric effects and of contributions of diamagnetic anisotropy. There is no conclusive evidence for (p-d)π conjugation.     

Stereochemical studies of 2-hydroxychromanones by 1H NMR spectroscopy

2-Hydroxychromanones (2a–2f) were synthesized by ring closing of 2-hydroxyacetophenones (1a, b) and 2-hyroxypropiophenones (1c–1f). In the case of 2-hydroxy-3-methyl-chromanones (2c–2f) a mixture of cis and trans isomers was obtained. The trans isomers are conformalionally homogeneous, the cis isomers exist in a conformational equilibrium. At room temperature the isomers are transformed into each other via opening of the heteroring. This process becomes faster in alkaline medium and the β-diketo form 4 can also be observed.     

1H and13C NMR spectra of biologically active compounds

The¹H and¹³C NMR spectra of diols of the hexachlorobicycloheptene and-heptadiene series, and also of the diacetates and sulfites corresponding to them, have been investigated. Criteria for the stereochemical assignment of the compounds mentioned on the basis of chemical shifts and spin-spin coupling constants have been determined.Institute of Chemistry, Bashkir Branch, USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 439–443, May–June, 1988.     

顺磁性镧系金属有机配合物的1H核磁共振研究

顺磁类的核磁共振研究大多是简单化合物,偏重理论方面的研究,对镧系配合物曾有报道。由于这类样品对空气和湿气极为敏感,在国内外研究顺磁性¹H谱甚少。本文研究了含氯桥的醚基取代环戊二烯镧系配合物二聚体的¹H化学位移,线宽,弛豫时间T₁和磁化率,从中找出了顺磁类有机镧系配合物¹H NMR的规律。     

19F and 1H NMR and ESR investigations of aryl-t-butyl nitroxides and nitronylnitroxides

¹H and ¹⁹F NMR and ESR spectra of several nitroxides have been recorded. The ¹⁹F couplings are sensitive to steric factors and this shows why the simple linear relationship a_F = O_eff^F· ?_C^π is not adequate. The π and σ spin delocalization mechanisms are demonstrated. The spin transmission via oxygen and sulphur is affected by geometry (efficiency of pπ-nπ overlap), pπ-dπ overlap only plays a role in positively charged S atoms (sulphones). The absolute sign of the proton coupling in an alkyl chain depends upon chain length and substituents. The syntheses of several stable nitroxides are described.     

Extended hopane derivatives in sediments: identification by 1H NMR

The sedimentary C₃₂ hopanoic acid $\text{3a}$, one of the most abundant in nature and of probable bacterial origin, has been isolated for the first time as a single component and characterised by ¹H NMR. The 17αH,21βH configuration of the C₃₁ alkane has been similarly confirmed.     

烯烃氢甲酰化催化剂活性物种的原位1H NMR研究

The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pressurized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃. The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Ph-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.     

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs (abbreviated XBAYs) were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the ¹H NMR chemical shifts (^δH(CH=N)) and ¹³C NMR chemical shifts (^δC(CH=N)) of the CH=N bridging group from di-substituted to multi-substituted XBAYs was made based on a total of 182 samples of XBAYs, together with the NMR data of other 129 samples of di-substituted XBAYs quoted from literatures. The results show that the substituent specific cross-interaction effect parameter \begin{document} $\left(\Delta\left(\displaystyle\sum\sigma\right)^2\right)$ \end{document} plays an important role in quantifying the ^δC(CH=N) values of XBAYs, but it is negligible for quantifying the ^δH(CH=N) values; the other substituent parameters also present different influences on the ^δC(CH=N) and ^δH(CH=N). On the whole, the contributions of X and Y to the ^δC(CH=N) of XBAYs are balanced, but the ^δH(CH=N) values of XBAYs mainly rely on the contributions of X.     

DMA水溶液的1H NMR研究

测量了N,N-二甲基乙酰胺(DMA)水溶液体系不同温度下全浓度范围的¹H NMR数据, 对体系中的缔合情况进行了讨论, 应用化学缔合模型求得了各缔合平衡常数K和缔合平衡的ΔH. 结合N,N-二甲基甲酰胺(DMF)和N-甲基乙酰胺(NMA)水溶液的研究结果, 发现酰胺自身结构和酰胺浓度是影响酰胺水溶液性质的主要因素.     

The 1H NMR spectra of methylmethoxyaluminium chloride and methylmethoxyaluminium iodide

It has been shown by means of ¹H NMR, IR and cryometrical measurements that, with oxygen bridges, Me(OMe)AlCl and Me(OMe)AII are trimers in solutions.Two isomers, cis and trans, are present, which are responsible for the multiple ¹H NMR spectra. The proton signals of MeAl and OMe groups are assigned in each isomer.