Two Novel Sub-skeleton Types of ent-Kauranoids from Isodon gesneroides

Two novel ent-kauranoids with new sub-skeleton types, gesneroidins G and H were isolated as white powder from the ether extract of the leaves of Isodon gesneroides through normal phase column chromatography. Their structures were elucidated as 3β,6α,7β-triacetoxyl-15-hydroxyl-14-oxo-ent- 15,16-seco-kaur-11,17-olide and Iα-hydroxyl-3β,6α,7β,11 β-tetraacetoxyl-ent-nor-15,17-kaur-8,16-olide on the basis of the spectral evidences including ID and 2D NMR spectra.     

微波辅助聚合物支载的有机反应

微波辐射下，聚合物支载的有机反应易于进行，操作简便，反应速率高，反应 时间短，产率高，纯度好，聚合物载体稳定，综述了微波辅助不溶性聚合物和可溶 性聚合物支载的有机反应。     

含呋喃环Schiff碱型大环化合物的合成及其与Ba^2+,Sr^2+配合行为

利用Mn^2+，Ba^2+及Sr^2+作为模板离子，合成了一类新型的含呋喃环系 Schiff碱型大环化合物，如L^1和配合物L^2Ba(ClO4)2，L^3Ba(ClO4)2和L^4Ba (ClO4)2.L^2-L^4的Ba^2+配合物经与NaSO4水溶液反应解络，得到自由配体L^2， L^3和L^4，配体L^2和L^3分别与Sr^2+作用，得到配合物L^2Sr(ClO4)2和L^3Sr (ClO4)2。上述大环配体和各种配合物均经元素分析，IR，^1H NMR，MS等证实了它 们的结构和组成。     

酶促酮酸酯还原合成(S)-2乙酰氧基十三烷

Bartelt等 [1] 于 1 989年首次从穆勒果蝇 (Drosophila mulleric)的雄性成虫体内分离出其聚集信息素 ,并确证其主要生物活性的成分为 (S) -构型的 2 -乙酰氧基十三烷 (1 ) ,而 (R) -构型无生物活性 .1 999年Hillbur等 [2 ,3 ] 发现碗豆瘿蚊 (Contarinia pisi)的雌性性信息素主要成分中也含有 (1 ) ,其对碗豆瘿蚊雄虫具有很强的性引诱作用 .有关 (1 )的合成报道较多的为酶促反应合成法 [4～ 7] .我们曾以 1 -苯砜基 - 2 -丙酮为原料经酶促还原反应合成了目标产物 ,此法尽管合成路线短 ,光学产率较高 ,但反应原料不易购得 ,且使用两摩尔比…     

高温下淀粉的凝胶化作用

凝胶化作用是淀粉及改性产品生产过程中存在的一种现象。淀粉凝胶化作用的结果导致了在其产品中产生了只溶胀但不溶解的颗粒,从而影响了淀粉产品的整体性能。文章初步探讨了淀粉在高温成型过程中凝胶化作用的方式和起因。结果表明,淀粉浆料在高温成型过程中所产生的凝胶团粒是淀粉不完整的凝胶化作用的结果,足量的水分和高温是形成较多的凝胶化淀粉颗粒的原因。     

异丙氧基-异羟肟酸-氧钒（V）配合物的合成、晶体结构和量子化学研究

以苯甲酰异羟肟酸为配体，首先合成四价氧钒化合物，以此为基础合成了标题 化合物，并用元素分析，红外光谱，~1H NMR，~(13)C NMR，~(15)V NMR，电子吸 收光谱等，分别对它进行了表征，其结构用单晶X射线衍射法测定，晶体属三斜晶 系，P1-bar空间群，所得晶体学参数为a = 1.1119(3) nm，b = 1.1735(3) nm，c = 0.8660(2) nm，α = 96.84(1)°，β = 106.93)(1)°，γ = 88.97(1)°，V = 1.0731(2) nm~3，D_c = 1.415 g/cm~3，Z = 2，F(000) = 478，μ = 5.06 cm~(-1)。采取ab initio(GTO-6-31d)方法对标题化合物的结构单元的成键情况进 行了分析，讨论了化合物的稳定性、分子轨道能量、原子静电荷分布等情况。     

Dispersion state and catalytic properties of vanadia species on the surface of V_2O_5/TiO_2 catalysts

The dispersion state and catalytic properties of anatase-supported vanadia species are studied by means of X-ray diffraction (XRD), laser Raman spectroscopy (LRS), H2 temperature-programmed reduction (TPR) and the selective oxidation of o-xylene to phthalic anhydride. The almost identical values of the experimental dispersion capacity of V2O5 on anatase and the surface vacant sites available on the preferentially exposed (001) plane of anatase suggest that the highly dispersed vanadium cations are bonded to the vacant sites on the surface of anatase as derived by the incorporation model. When the loading amount of V2O5 is far below its dispersion capacity, the dispersed vanadia species might mainly consist of isolated VOx species bridging to the surface through V-O-Ti bonds. With the increase of V2O5 loading the isolated vanadia species interact with their nearest neighbors (either isolated or polymerized vanadia) through bridging V-O-V at the expenses of V-O-Ti bonds, resulting in the increase of the ra     

镉(Ⅱ)与对苯二甲酸和2,2′-联吡啶配合物光谱性质的理论研究

对镉(Ⅱ)与对苯二甲酸和2,2′-联吡啶配合物进行几何优化,在优化构型的基础上分析了其吸收光谱.结果表明主要贡献的激发态为16,17和26激发态而不是第一激发态,振子强度f为0.2052,0.3202和0.3234,对应的吸收波长为308.57,307.33和258.35 nm,与实验值310和253 nm相近.     

高含水聚乙烯醇弹性体

本文介绍了用反复冻结～融溶过程制备高含水聚乙烯醇弹性体的方法,并测定了该弹性体的机械、溶解和溶胀性能。结果表明,该弹性体可同时具有很高的含水率(85—90％)和较高的抗张强度(10~5—10~6Pa),且在37℃的水中有良好的稳定性能。     

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.