红外和核磁共振法鉴定聚醚型聚酯的组成结构

利用红外吸收光谱及核磁共振波谱仪的一维和二维技术对一种未知聚合物试样进行鉴定。由核磁共振二维技术分析得出聚醚酯的序列结构及其分布。结果表明:该未知聚合物试样为聚醚酯弹性体,由对苯二甲酸、间苯二甲酸、新戊二醇、乙二醇、聚四氢呋喃醚共聚而成。     

Isotope-specific analysis of neutron-irradiated lithium aluminate ceramics by nuclear magnetic resonance spectroscopy

The effects of neutron irradiation on lithium aluminate ceramics and the transport and incorporation of tritium into surrounding components are primary concerns in the development of materials for use in tritium production. The high specific activity and volatility of the tritium in activated samples greatly increase the challenges of experimental analysis. This paper reports the determination of structural forms and concentrations of ³H and ⁶Li in irradiated and nonirradiated LiAlO₂ by nuclear magnetic resonance spectroscopy. The experiments find tritium uniformly distributed in hydroxyl groups bridging aluminum centers and lithium in four- and six-coordinated sites. These results demonstrate that measurements can be performed in a nondestructive, safe manner to obtain isotope-selective, quantitative information even on highly hazardous materials.     

核磁共振法测定涤纶长丝含油率

采用核磁共振仪测试涤纶长丝含油率,初步探讨了其在生产过程中的应用。结果表明:与传统洗涤法相比,核磁共振法具有快速、简便、试样不需制备、不称重、不需溶剂的优点,且测试精密度和准确度高。     

Oxidative polymerization of phenylenediamines by enzyme and magnetic properties of the products

Oxidative polymerization of m-phenylenediamine was carried out using H₂O₂ as an oxidant and horseradish peroxidase as a catalyst in mixtures of aqueous buffer solution and 1,4-dioxane or in reversed micellar solutions. When the reaction mixture was brought into contact with a stainless steel stick, the obtained polymer responded to a permanent magnet at room temperature in the air. From the ICP emission spectroscopic analysis, it was found that these polymers contained small amounts of transition metals, such as Fe and Ni. The magnetic properties of the obtained polymers were studied with a superconducting quantum interference device (SQUID). The M (magnetization)–H (magnetic field) curves showed sigmoid behavior at 300 K, but did not exhibit a residual magnetization and a coercive force. These properties resembled those of soft ferromagnetic materials. The ferromagnetic behavior was indicated even at 800 K. Polymers of o- and p-phenylenediamines exhibited lower values of saturation magnetization than polymers of m-phenylenediamine. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 717–721, 1998     

Determining the blend level of mixtures of biodiesel with conventional diesel fuel by fiber-optic near-infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy

Biodiesel, defined as the alkyl esters (usually methyl esters) of vegetable oils, is miscible with conventional diesel fuel at all blend levels. Until the present time, no rapid and reliable analytical method has existed for determining the blend level of biodiesel in conventional diesel fuel. In the present work, near-infrared (NIR) and nuclear magnetic resonance (NMR) spectroscopies were used to determine the blend level of biodiesel in conventional diesel fuel. Several regions in the NIR region (around 6005 cm⁻¹ and 4800–4600 cm⁻¹) are suitable for this purpose. The method is rapid and easy to use, and does not require any hardware changes when using the same instrument for monitoring the biodiesel-producing transesterification reaction and determining biodiesel fuel quality. In ¹H NMR spectroscopy, the integration values of the peaks of the methyl ester moiety and the aliphatic hydrocarbon protons in biodiesel and conventional diesel fuel were used for determining blend levels. The results of NIR and NMR blend level determinations are in good agreement.     

酶催化水溶性导电聚苯胺的模板导向合成与表征

对辣根过氧化物酶(HRP)催化水溶性导电聚苯胺的合成进行了研究.以聚乙烯磺酸钠(PVS)作为反应的聚阴离子模板.详细地研究了反应体系的pH值、H2O2浓度及苯胺与PVS的摩尔比对苯胺聚合的影响.用UV-vis-near-IR、FTIR及四探针电导率测试仪对产物进行了表征,并与其他模板聚合产物进行了比较.研究结果表明,PVS可作为HRP催化苯胺聚合的模板,合成的PVS/PANI的电导率为4.78×10-1S·cm-1,反应体系的pH值应控制在4.0～5.0,H2O2浓度以20 mmol·L-1为宜,PVS与苯胺的摩尔比应控制在1～1.5.     

Two-dimensional nuclear magnetic resonance of resins

A group of resins was synthesised from a series of phenols and aldehydes, and their structures comprehensively deduced from two-dimensional nuclear magnetic resonance spectroscopy (2-D NMR). Correlation spectroscopy, in particular carbon-proton heteronuclear chemical shift correlation spectroscopy, was shown to be especially incisive in assigning structural features to the NMR signals. The method has permitted fuller structural characterisation of these materials than was heretofore possible, and has identified, inter alia, methylene and methyleneoxy bridges unequivocally: complex substitution patterns in the phenol-derived aromatic rings have also been elucidated. It is demonstrably possible to apply the same techniques to similar complex resin structures, and to utilise these structural insights to determine the mechanistic processes involved in their syntheses.     

Elaidic acid in rat liver identified by gas chromatography and nuclear magnetic resonance spectroscopy

Fatty acid composition has been commonly determined by gas chromatography (GC). In the most commonly used methods, the lipids must be converted into methyl esters or other derivatives of the fatty acids before being analyzed by GC. Nuclear magnetic resonance (NMR) spectroscopy has become one of the most promising methods to determine organic structures, providing useful data for analyzing the fatty acid composition of edible vegetable oils. The major advantage of NMR is that identification of each fatty acid is carried out by evaluation of particular signals. We report in this work the fatty acid profile of rat liver after consumption of diets containing different concentrations of partially hydrogenated vegetable fat. The fatty acid composition was identified by GC, and trans fatty acids were also identified by ¹³C NMR spectroscopy. The results obtained by the ¹³C NMR method were close enough to those obtained by conventional GC.     

Monitoring a progressing transesterification reaction by fiber-optic near infrared spectroscopy with correlation to 1H nuclear magnetic resonance spectroscopy

Biodiesel is a promising alternative diesel fuel obtained from vegetable oils, animal fats, or waste oils by transesterifying the oil or fat with an alcohol such as methanol. In an extension of previous work, fiber-optic near infrared spectroscopy was used to quantitatively monitor the transesterification reaction (6-L scale) of a vegetable oil (soybean oil) to methyl soyate. The results were correlated with ¹H nuclear magnetic resonance spectroscopy. The method described here can be applied to the transesterification of other vegetable oils.     

Structure of initial and ultimate chain units of polydienes obtained with rare-earth catalysts as revealed by H nuclear magnetic resonance spectroscopy

The structure of initial and ultimate chain units in polybutadiene and polyisoprene was studied by means of ²H nuclear magnetic resonance spectroscopy. Polydienes were prepared with a neodymium catalyst; quenching was performed with deuteromethanol. The enrichment of quenched ultimate units by trans-1,4 structures at the expense of cis-1,4 structures at high polymer yields was observed. When using diisobutylaluminium deuteride DAl(i-Bu)₂, as chain transfer agent, it was shown that the principal site of chain transfer reaction was the Al-D bond. The initial unit of polybutadiene was predominantly of trans-1,4 structure.     

Structure of initial, ultimate and inner chain units of polybutadiene obtained with a rare-earth catalyst as revealed by C nuclear magnetic resonance spectroscopy

The structure of initial, ultimate and inner chain units in polybutadiene produced with NdCl₃. 3(i-PrOH)---HAl(i-Bu)₂was studied by means of ¹³C nuclear magnetic resonance spectroscopy. Initial units are shown to be predominantly of trans-CH₃CH=CHCH₂--- structure. Conversely, 90% of inner units have cis configuration. Ultimate units obtained by quenching with H₂O (D₂O) are predominantly of 1,2 structure. On the basis of the data obtained, the polymerization mechanism was discussed.     

Quantitative assessment of alkyl chain branching in alcohol-based surfactants by nuclear magnetic resonance

Surfactants with branched hydrophobes have gained considerable interest, since these can be used in formulations for laundry cleaning at a wide range of conditions. The claims range from improved dissolution rate to hardness tolerance and stain removing efficacy. In contrast to the historically known heavily branched surfactants, novel branched surfactants are less compromised by increased biodegradability. These properties find their basis in the structural characteristics of the hydrophobe, such as number, position, and type of alkyl chain branches. Our current understanding of structure-property relations, however, is hampered by the lack of generic methodology needed to obtain structural data on hydrophobe branching. A nuclear magnetic resonance (NMR) approach was developed by which we could obtain a comprehensive set of quantitative hydrophobe branching parameters in alcoholbased surfactants. The ¹³C and ¹H NMR spin systems of hydrophobe branched species were assigned by means of twodimensional NMR techniques. These assignments allowed the quantitative assessment of these branched species by straight-forward signal integration in the ¹H and ¹³C NMR spectra. The quantified NMR data can be used to understand product performance and the biodegradation of surfactants with branched hydrophobes.     

定量核磁共振法研究进展

核磁共振法广泛应用于有机化合物的定性分析,但是它在化合物纯度定值、含量测定中也具有很重要的作用,分为一维谱(1H、13C、14N、15N、19F、31PNMR)、二维谱(J-分辨、1H-1H、1H-13C、DOSY)、液相色谱-核磁共振联用法(LC-NMR)、固体NMR等NMR类型。其中,1H谱最常用,其他一维谱对不同化合物各有其优势。二维核磁共振法对于在一维谱图中信号严重重叠的复杂样品的定量分析非常重要。LC-NMR联用技术将高效的分离手段与NMR联用,可以获得复杂样品的信息。介绍了各类定量核磁共振法在各领域的研究进展。     

Nuclear magnetic resonance spectroscopy and reversed-phase high-performance liquid chromatography of peracetylated digalactosyldiacylglycerols

A simple method for the peracetylation of digalactosyldiacylglycerols is described. The peracetylated compounds were isolated by thin-layer chromatography and subjected to nuclear magnetic resonance spectroscopy for structure elucidation. The proton signals at acetylated sites are shifted downfield compared to the nonderivatized compounds, resulting in improved resolution. The peracetylated compounds were also subjected to molecular species analysis by reversed-phase high-performance liquid chromatography. The chromatography behavior of the peracetylated compounds was similar to that of triacylglycerols, displaying narrow and symmetrical peaks yielding a highly resolved molecular species profile.     

Radiation degradation of epoxidized natural rubber studied by solid‐state nuclear magnetic resonance and infrared spectroscopy

The mechanism of radiation‐induced structural changes in epoxidized natural rubber was investigated using nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Samples were irradiated both under vacuum and in air. Because the rubbers crosslinked during irradiation, solid‐state NMR had to be used. The cross polarized/magic angle spinning NMR spectra were used to calculate the radiation yields. Ring opening of the epoxy groups was found to occur during irradiation. Most of the crosslinking was due to epoxy group ring opening, and very little or no C C crosslinking was observed. © 2000 Society of Chemical Industry     

Applications of in situ magnetic resonance techniques in chemical reaction engineering

NMR spectroscopy is now a well‐established technique for the in situ study of surface chemistry and the chemical processes occurring during catalytic reactions. Developments in probe design are making the sample environments ever closer to the operating conditions of the catalyst in industrial use. In parallel with these advances there is an increasing interest in the application of field gradient magnetic resonance techniques, namely pulsed gradient spin echo (PGSE) NMR and magnetic resonance imaging (MRI), to in situ studies of mass transport processes in catalysts and reactors. An overview of the recent developments in in situ NMR spectroscopy, PGSE NMR and MRI studies in application to catalysis and reaction engineering is presented and the potential of these techniques in the numerical modelling of catalytic processes and reactor design is highlighted. This revised version was published online in August 2006 with corrections to the Cover Date.     

共聚酯中间苯二甲酸含量的NMR测定

介绍了共聚酯中间苯二甲酸含量的测定方法之一———核磁共振法(NMR),表明对于间苯二甲酸含量较低的共聚酯,采用13C谱的测定结果较好。     

Investigations of polymer chains in oriented fluid phases with deuterium nuclear magnetic resonance

Deuterium nuclear magnetic resonance (D n.m.r.) is a potentially powerful technique for exploring molecular structural and dynamical properties of polymer chains in bulk fluids and concentrated solutions. A variety of systems can be investigated (the solid state, elastomeric networks, sheared polymer fluids, chain solutes in liquid crystal solvents, and polymeric liquid crystals), over a wide range of dimensions (local chain properties, rotational isomeric state parameters, behaviour between network junctions or entanglements, evolution of tube distributions, and domain sizes of homogeneous chain alignment). A coarse comparison of low molar mass liquid crystals with condensed phases of entangled polymer fluids and elastomeric networks illustrates the key features of the D n.m.r. technique and establishes a common framework for interpreting experiments.     

Conifer seed oils: Distribution of Δ5 acids between α and β chains by13C nuclear magnetic resonance spectroscopy

Nine seed oils from three different conifer families, already examined by gas chromatography and known to contain diene, triene, and tetraene C₁₈ and C₂₀Δ5 acids, have been reexamined by high-resolution¹³C nuclear magnetic resonance spectroscopy. The Δ5 acids are apparent only in the α-chains. This location is independent of chainlength, double-bond number, and the species considered and is probably a general factor of conifer seed oils. The spectra confirm the presence of oleic, linoleic, α-linolenic, and of Δ5 acids and give quantitative information about (total) n-6, n-3, and Δ5 acids that is in accord with that obtained by gas chromatography.     

Characterization of fluorine-, aluminum-, silicon-, and phosphorus-containing complexes in wet-process phosphoric acid using nuclear magnetic resonance spectroscopy

Wet-process phosphoric acid is one product of the reaction between phosphate rock and sulfuric acid. The limiting step in this process occurs when the acid is filtered from the reaction slurry, which also contains calcium sulfate (gypsum). The acid-soluble impurities present in the phosphate rock (e.g., fluorine, silicon, and aluminum) form complexes in wet-process acid which can alter the optimum size and habit of gypsum crystals, thereby reducing the filtration rates. Fluorine-containing complexes are strongly suspected of being potent modifiers of the crystal habit of gypsum. However, the identities of the complexes responsible for the habit modification have not been established. The identities of the complexes formed in phosphoric acid (28% P₂O₅) containing additions of fluorine (HF and H₂SiF₆) and aluminum [Al(NO₃)₃ · 9H₂O or AlF₃ · 9H₂O] were established in this study by using fluorine-19 (¹⁹F) and phosphorus-31 (³¹P) nuclear magnetic resonance (NMR) spectroscopies. Peaks due to aluminum fluoride, fluorosilicate, and fluoroaluminum phosphate complexes were observed in the NMR spectra recorded from these solutions. In addition, the¹⁹F and³¹P NMR spectra of wet-process acids were recorded. These spectra contained peaks assigned to the hexafluorosilicate ion (major species), along with aluminum fluoride and fluoroaluminum phosphate complexes (minor species).