烯丙基卤和锡与醛, 酮反应合成高烯丙基醇

烯丙基溴或烯丙基碘和锡能以较高的产率与含有羟基、酚羟基、硝基、溴等活性基团的羰基化合物作用合成相应的高烯丙基醇, 文中讨论了不同卤素以及溶剂性质、水的含量对反应的影响。     

Thermal Properties and Fire Resistance of Jute-Reinforced Composites

The thermal behaviour, fire resistance and mechanical properties of jute-reinforced composites with vinylester and resol matrix were studied. Organically modified clay was added to the polymeric matrix in order to enhance the properties of the composites. An inhomogeneous distribution of the nanoreinforcement in the polymer was observed by X-ray diffraction. Thermogravimetric analyses revealed that the addition of clay to the resol resin by sonication enhanced the thermal resistance of the jute-reinforced composite at temperatures higher than 300°C. The fire resistance of the composites was evaluated by means of a cone calorimeter. A diminution in the peak of the heat release rate was observed when clay was added to the polymeric matrix. On the other hand, neither the time to ignition nor the total heat evolved was significantly reduced by the clay addition. Additionally, an increment in the flexural modulus as well as in the flexural strength of the resol composites was observed when the clay was added to the matrix. The fiber–matrix interface of the composites was studied by scanning electron microscopy. It was observed that as the clay dispersion degree was increased the interface quality was diminished in the resol composites.     

Enhancing the Fibre Matrix Adhesion of Natural Fibre Reinforced Polypropylene by Electron Radiation Analyzed with the Single Fibre Fragmentation Test

The effects of electron radiation on natural fibre reinforced polypropylene have been analyzed with the single fibre fragmentation test. Specimens of single hemp, flax, ramie and cotton fibres/fibre bundles embedded in a polypropylene sheet were irradiated with electron radiation of 10 MeV with intensities of 5, 15 and 33 kGy. The radiation led to a strain reduction of the polypropylene but did also improve the adhesion between polymer and flax, hemp and cotton fibres/fibre bundles. The critical fragmentation length and the interfacial shear strength (IFSS) of the composite specimens have been determined showing a clear increase of the IFSS of up to 50% compared to specimens with applied coupling agents. Due to the high strain reduction of the PP at intensities of 15 and 33 kGy the different fibres could only be compared at 5 kGy. The ramie fibre specimens could be analyzed at 5 and 15 kGy intensity showing higher IFSS values at the higher intensity. A possible explanation for the improvement is the forming of radicals with the cellulose chains of the natural fibres and the polypropylene molecules leading to crosslinking and, therefore, better adhesion between the different components.     

Viscoelasticity and morphology of an organic hybrid of chlorinated polyethylene and N,N′-dicyclohexyl-2-benzothiazolyl sulfenamide

The viscoelasticity and morphology of an organic hybrid of chlorinated polyethylene (CPE) and N,N′-dicyclohexyl-2-benzothiazolyl sulfenamide (DBS) were studied by means of tensile and shear complex modulus and differential scanning calorimetry (DSC) analysis. Tensile and shear loss modulus (E″ and G″), which are shown as indexes of vibration damping performance, showed one peak corresponding to the glass transition. The peak maximum values (E″_max and G″_max)increased in proportion to DBS content ( _DBS) and the slope of E″_max against _DBS became steep above a certain DBS content, i.e. the critical DBS content ( _c). A high damping material was obtained by the addition of DBS, especially when DBS content was higher than _c. These increases in loss moduli below and above _c are caused by the interaction between CPE and DBS molecules and the friction between DBS molecules, respectively. It was found that CPE/DBS is a compatible blend at all DBS contents from the analysis of the glass transition temperature with DSC. Furthermore, the influence of chlorine content in CPE on those characteristics was investigated. Higher chlorine content led to lower _c, a decrease in E″ below _c and an increase in E″ above _c. These results are due to the increase in the number of dichloromethylene units (CCl₂), which reduces the α-hydrogen atom in CPE.     

青蒿素及其类似物的合成研究-由青蒿素降解产物重组青蒿素

青蒿素1是中药青蒿(Artemisia annua L.)中的抗疟有效成份,它具有与其他抗疟药完全不同的独特结构,近年来,李英等已报道了从青蒿素合成得一系列疗效更高的衍生物,而Schmid等和许杏祥等曾分别独立完成了青蒿素的合成。由于合成其它青蒿素衍生物的需要,我们计划发展较为实用的方法。鉴于目前易于获得天然的青蒿素,因此我们在研究全合成的同时,也探索利用由青蒿素获得接力中间体重组青蒿素和合成青蒿素衍生物。通过酸性降解研究,我们从青蒿素经两步可制得双酮酯化合物3,产率较高。该化合物保持青蒿素中原有的构型,因此是一个理想的接力中间体,本文报道由此化合物重组青蒿素的工作。     

α-羟基二茂铁类衍生物的合成及其晶体结构

通过甲酰基二茂铁与苯乙酮，硝基甲烷及丙酮的缩合反应，我们制得了其缩合产物-α-羟基-β-羰基化合物。并对甲酰基二茂铁与苯乙酮的缩合产物进行了X射线单晶结构分析。结果表明：该晶体属于单斜晶系，空间群为P 2~1/n，a=0.6022(1)，b=2.735(1)，c=0.9416(1)nm，β=99.02(1)°，V=1.532(1)(nm)^3，Mr=334.20，Z=4，Dx=1.45g/cm^3，μ=9.68cm^-^1，F(000)=696。     

用β-CD构筑琥珀酸脱氢酶的研究

用β-CD，马来酸酐，氯乙酸和三氯化铁反应，合成了双-[6-氧-(β-羧甲基-丁二酸-1,4-单酯-4-)]-β-CD·Fe^3^+配合物(简称模拟酶)。以此模拟酶模拟琥珀酸脱氢酶，将琥珀酸氧化脱氢生成延胡索酸，同时，又将甲苯氧化成苯甲醛和苯甲酸。     

应用亲核性离子交换树脂(PhS^-型)制备苯硫醚

用强碱性离子交换树脂(^-OH型)与PhSH反应，得到一种离子交换树脂支载的PhS^-试剂，它与卤代物和α,β-不饱和醛酮很容易反应，得到相应的苯硫醚，产率较高或中等。     

通过碳-碳键形成杂环的合成方法及应用

综述了包括五种带电荷中间体通过碳-碳键形成杂环的反应:(1)亚胺翁离子-乙烯基硅烷的环化反应,(2)亲核试剂引发的亚胺翁离子-炔的环化反应,(3)缩醛-烯烃的环化反应,(4)aza-Cope-Mannich反应,(5)通过Prins-pinacol重排合成环醚的反应;以及这些反应在有机合成特别是在天然产物全合成研究的进展。     

稀土金属有机化学的最新进展

综述了我们近年来在稀土金属有机化合物的合成,结构以及它们在有机合成和极性单体聚合中的应用的新进展。