Effect of acidity in TS-1 zeolites on product distribution of the styrene oxidation reaction

The role of Bronsted acidity of titanium silicalite zeolite (with different ratios of Si/Ti) in oxidation reactions of styrene has been investigated and discussed. For zeolites with Si/Ti > 42, most of the titanium is in the zeolite framework. These framework titanium species, which act both as the isolated titanium centers and as Bronsted acidity centers (together with the Bronsted acidity produced by the tetrahedral aluminum impurity introduced during synthesis), can catalyze both the epoxidation and the succeeding rearrangement reactions, thus promoting the formation of phenylacetaldehyde. With an increase in the titanium content of the zeolite, titanium will tend to stay outside the zeolite lattice, except for the TiOx nanophases which can be occluded in the zeolite channels or on the external surface. These non-framework titanium species are favorable for the carbon-carbon bond scission, leading to the production of additional benzaldehyde. The catalytic performances of these zeolites with different Si/Ti ratios are correlated here with their structural information by using solid-state NMR and UV-Vis methods. (C) 2003 Elsevier B.V. All rights reserved.

由一株真菌产生的抑制血管细胞粘附分子-1基因表达的活性物质的研究

以血管细胞粘附分子-1（VCAM－1）基因为靶位点，使用含有荧光素酶报告基因的转染细胞株筛选模型M-4细胞从微生物的代谢产物中高通量筛选能够抑制VCAM－1基因表达的生物活性物质，以期找到能够治疗诸如类风湿性关节炎等免疫性疾病的新型药物。在筛选过程中使用有机溶媒萃取、ODS反相柱层析、HPLC制备等方法，从真菌FO－5897的发酵液中分离到了一个对测活用细胞株的荧光素酶报告基因的表达有中等强度抑制作用的化合物，其IC50为13．8μmol／L，经各种理化性质及1H－NMR分析确定该化合物与文献报道的具有降血脂和抗癌作用的化合物Ascofuranone的结构相同。

Preparation of a blocked isocyanate compound and its grafting onto styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer

The epsilon-caprolactam was used to block the isocyanate group to enhance the storage stability of allyl (3-isocyanate-4-tolyl) carbamate. The spectra of FTIR and NMR showed that blocked allyl (3-isocyanate-4-tolyl) carbamate (BTAI) possesses two chemical functions, an 1-olefin double bond and a blocked isocyanate group. The FTIR spectrum showed BTAI could regenerate isocyanate group at elevated temperature. DSC and TG/DTA indicated the minimal dissociation temperature was about 135 degrees C and the maximal dissociation rate appeared at 226 degrees C. Then the styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer (SEBS) was functionalized by BTAI via melt free radical grafting. The effect of temperature, monomer and initiator concentrations on the grafting degree and grafting efficiency was evaluated. The highest grafting degree was obtained at 200 degrees C. The grafting degree and grafting efficiency increased with the enhanced concentration of BTAI or initiator.

1-烯丙基-3-甲基咪唑离子液体单体与丙烯腈共聚行为的研究

以1-烯丙基-3-甲基咪唑盐酸盐([AMIM]Cl)作为离子液体单体,偶氮二异丁腈作为引发剂,二甲基亚砜为溶剂,实现了与丙烯腈(AN)在不同反应条件下的自由基共聚合.研究了AN/[AMIM]Cl二元共聚合的动力学,得到了相应的竞聚率数据(rAN=8.11,r[AMIM]Cl=0).用1H-NMR、GPC、DSC、TGA等手段对共聚物进行了表征.通过对AN/[AMIM]Cl二元共聚及AN/IA/[AMIM]Cl三元共聚的研究发现,[AMIM]Cl在与丙烯腈共聚时具有双重作用,一部分离子单体进入到共聚物的分子链中调节其亲水性及可纺性,剩下的大部分留在纺丝液中可显著降低纺丝液的黏度,从而使高分子量高固含量纺丝液的纺制成为可能,有望得到高性能的碳纤维原丝.

间同1,2-聚丁二烯的结构和结晶动力学研究

间同1,2-聚丁二烯(s-PB)由丁二烯用Fe(2-EHA)3/Al(i-Bu)3/DEP作催化剂,在己烷溶剂中50℃下聚合制备.用13C NMR谱方法测定的1,2-结构含量为89.3%,间同结构为86.5%;X射线测得聚合物的结晶度约为68%.非等温结晶动力学研究采用DSC方法,改进的Avrami方程可以很好地分析s-PB非等温结晶过程的主期结晶,表明其结晶过程是自成核,三维球形生长.Ozawa方程不适合分析s-PB非等温结晶动力学;Avrami和Ozawa方程结合的方法可以很好地描述s-PB非等温结晶过程,指数a为1.138,F(θ)随着结晶度的提高而增大;并计算了s-PB的结晶活化能.