茂金属线性低密度聚乙烯的组成均匀性

茂金属线性低密度聚乙烯的组成均匀性徐旭荣徐君庭封麟先陈伟（浙江大学高分子科学与工程学系杭州３１００２７）（中国石化总公司石油化工科学研究院北京１０００８３）关键词线性低密度聚乙烯，组成均匀性，茂金属催化剂８０年代以来，茂金属催化剂得到迅速发展．...     

茂金属聚乙烯的流变性与加工性

研究了丁烯 １ 共聚的茂金属聚乙烯（ｍＰＥ） 的流变性,发现茂金属聚乙烯的窄分子量分布导致它在挤出加工剪切速率范围里熔体粘度高、对剪切敏感性差以及熔体从牛顿型转为非牛顿型所需的剪切速率、转变应力高,在挤出加工条件下流动性差,加工困难．对茂金属聚乙烯（ｍＰＥ） 进行改性制得ＭｍＰＥ,ＭｍＰＥ 熔体对温度、剪切速率的敏感性提高,在加工温度、加工剪切速率范围里的表观粘度降低,加工流动性得到了显著的改进,可在普通聚乙烯加工设备上,制备性能优良的茂金属聚乙烯薄膜制品．     

茂金属催化线性低密度聚乙烯的光氧化稳定性

茂金属催化线性低密度聚乙烯的光氧化稳定性;茂金属线性低密度聚乙烯;Ziegler-Natta线性低密度聚乙烯; 光氧化降解     

茂金属支化聚乙烯的结构、形态与熔融行为

综述了茂金属支化聚乙烯的形态，结构和熔融行为，详细讨论了支链大小和含量以及分子量对其物理性质的影响。     

茂金属聚乙烯分子链流变学模型研究进展

茂金属聚乙烯的分子链长支化结构对其流变特性有重要影响，长支链可以使熔体弹性和剪切变稀效应明显增强。本文介绍了茂金属聚乙烯分子链模型建立的理论依据，从流变学角度综述了近年来茂金属聚乙烯分子链结构模型的研究进展，阐述了有关的长链支化结构模型及其与流变性能的关系。     

茂金属聚乙烯的非等温结晶动力学

对茂金属催化和传统工艺生产的聚乙烯的非等温结晶行为进行了研究,用ＤＳＣ测试了两种聚乙烯的非等温结晶过程,对所得数据分别用Ｏｚａｗａ方程和莫志深方法进行了处理,发现：由于茂金属聚乙烯有着较高的立构规整性．所以虽然它的分子链较长,但结晶速率高于传统聚乙烯,两种聚乙烯非等温结晶过程中的成核和生长机理也不同,茂金属聚乙烯的生长维数高于传统聚乙烯     

茂金属聚乙烯的非等温结晶行为

茂金属聚乙烯的非等温结晶行为曾继军李育英何嘉松＊（中国科学院化学研究所工程塑料国家重点实验室北京１０００８０）关键词茂金属聚乙烯非等温结晶ＫｅｙｗｏｒｄｓＭｅｔａｌｏｃｅｎｅｐｏｌｙｅｔｈｙｌｅｎｅＮｏｎｉｓｏｔｈｅｒｍａｌｃｒｙｓｔａｌｉｚａｔｉｏ...     

茂金属 乙烯的流变性与加工性

研究了丁烯－１共聚的茂金属聚乙烯（mＰＥ）的流变性,发现茂金属聚乙烯的窄分子量分 布导致它在挤出加工剪切范围里熔体粘度高、对剪切敏感性差以及熔体从牛顿型转为非牛顿型所需的剪切速率、转变应力高,在挤出加工条件下流动性差,加工困难。对茂金属聚乙烯（mＰＥ）进行改性制得ＭmＰＥ,ＭmＰＥ熔体对温度、剪切速率的敏感性提高,在加工温 度、加工剪切范围里的天观粘度降低,加工流动性得到了显著的改进,可在普通聚乙烯加工     

茂金属聚乙烯的支化非均匀性与结晶形态

以美国Exxon公司生产的茂金属短支链聚乙烯 (SCBPE)为研究对象 ,用DSC热分级方法研究了不同支链含量聚乙烯的支化非均匀性 ,并用TEM表征茂金属聚乙烯在不同条件下熔体结晶的形态 .SCBPE经逐步结晶分级后 ,其DSC熔融曲线出现多峰 ,表明茂金属SCBPE仍具有很大的非均匀性 .支链含量愈高 ,熔点愈低 ,非均匀性增加 .SCBPE的晶体形态随平均支链含量的增加片晶厚度减小 ,片晶尺寸分布增加 ;含量较低时 ,SCBPE在不同温度下均生成球晶结构 .随结晶温度的降低支链含量较多的分子也能参与结晶 ,故生成的片晶厚度减小 .从相分离的熔体中结晶 ,大尺度的片晶集聚体间的分离和小尺度的片晶之间相分离同时存在 .     

界面键接的茂金属聚乙烯/聚合型改性蒙脱土纳米复合材料的超临界二氧化碳发泡

研究了界面具有化学键接的茂金属聚乙烯/聚合型改性蒙脱土(mPE/P-MMT)纳米复合材料的流变学行为。结果表明,与均聚聚乙烯及非界面键接的茂金属聚乙烯/十二铵改性蒙脱土(mPE/12-MMT)复合材料相比,mPE/P-MMT纳米复合材料具备由聚乙烯基体与P-MMT所组成的网络结构,因此具有较高的熔体强度(在190℃时的熔体强度为12.0cN)。用超临界二氧化碳作发泡剂对它们的发泡性能进行对比,mPE/P-MMT纳米复合材料具有更高的发泡倍率(可达14.7),其最佳发泡温度为142℃。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.