以相转移方法合成植物生长抑制剂-Paclobutrazol

用相转移催化的方法合成了(2RS,3RS)-1-对-氯苯基-2-(1,2,4-三唑-1-基)-4,4-二甲基-3-戊醇(Paclobutrazol)(1)。氯代片呐酮先与1,2,4-三唑反应,生成α-三唑基片呐酮(2),后者与对-氯苄卤反应生成三唑酮(3),再用硼氢化钾还原得1。1是有效的植物生长抑制剂和杀菌剂。     

纳米TiO2在空心陶瓷微球上的固定化及光催化分解辛烷

纳米ＴｉＯ２在空心陶瓷微球上的固定化及光催化分解辛烷方佑龄＊赵文宽尹少华董庆华孙育斌（武汉大学化学系武汉４３００７２）（武汉工业大学分析测试中心武汉）关键词光催化分解，二氧化钛，空心陶瓷微球，固定化，辛烷１９９６－０８－２６收稿，１９９６－１１－１１...     

The thermo-oxidative degradation of metallocene polyethylenes: Part 2: Thermal oxidation in the melt state

The thermo-oxidative melt degradation of different metallocene polyethylenes (mPEs) was investigated in a torque rheometer open to air at 225 °C and 10 rpm. The mPEs differed essentially according to their initial melt index, molar mass distribution, density and ash content, but one characteristic was changed at a time in order to assess the influence of each specific property in the thermo-oxidative degradation of the PEs investigated. Crosslinking was found to dominate at the early stages of degradation during mastication for most polymers where reactions of alkyl radicals to vinyl groups were considered to be the dominant reaction. Furthermore, discolouration was attributed to both excessive levels of catalyst residues and extensive formation of conjugated systems. Finally, it was concluded that the polymer melt viscosity, i.e., molar mass and shape of molar mass distribution, appeared to govern the processing stability of the mPE. These results confirm the importance of shear as the major source for initiation of free radicals formed by homolytic fission caused via mechanical cleavage of polymer chains.     

PREPARATION OF NOVEL POLYETHYLENE-graft-POLY(4-VINYLPYRIDINE)-SUPPORTED METALLOCENE CATALYSTS FOR ETHYLENE POLYMERIZATION

Polyethylene (PE) grafting 4-vinylpyridine copolymers has been produced as powders of different rushes by theirradiation method. After treatment with methylaluminoxane (MAO), the copolymers were used as supports for Cp_2ZrCl_2catalyst Results of X-ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, ultraviolet spectroscopy andscanning electron microscope measurements show that the catalytic sites have been linked through MAO on the PE-graft-4-vinylpyridine (PEVP). The percentages of grafting 4-vinylpyridine and supported Cp_2ZrCl_2 depend on the size ofpolyethylene powder. The smaller the polyethylene powder, the more percent of 4-vinylpyridine groups and Cp_2ZrCl_2 existon the polyethylene chains, and the PEVP-supported catalyst has a relatively high activity for ethylene polymerization.     

Intramolecular Cannizzaro desymmetrization of tetraethylene glycol assisted by a cation binding template

The synthesis of desymmetrized tetraethylene glycol possessing a benzyl alcohol and a benzoic acid end group via a Cannizzaro reaction is reported. The barium cation template used was found to be essential for a successful transformation.     

双离子AB交联型聚醚类固体电解质及其电流变液的性能

将α，ω－双甲基丙烯酰氧基封端的聚乙二醇与高氯酸锂络合，分别用溶液聚合和反相悬浮聚合合成了双离子ＡＢ交联型聚醚类高分子固体电解质（ＡＢＣＰＥ２）及其组成的无水电流变（ＥＲ）液．研究了ＡＢＣＰＥ２本身的离子导电性和含ＡＢＣＰＥ２的ＥＲ液的活性和电性能，并用扫描电镜表征了ＥＲ液中的粒子．获得了离子导电率高达８．０×１０－５Ｓ／ｃｍ（２５℃）的高分子固体电解质和活性较高的无水ＥＲ液．     

New types of soluble polymer-supported bisphosphine ligands with a cyclobutane backbone for Pd-catalyzed enantioselective allylic substitution reactions

A highly efficient and practical optical resolution of anti head-to-head racemic coumarin dimer 7 has been achieved by molecular complexation with TADDOL, (-)-8, through a hydrogen bonding interaction to afford the corresponding two enantiomers, (-)- and (+)-7, in 70 and 75 % yields, respectively, with >99 % ee. Starting from enantiopure (-)-7, a new type of C2-symmetric bisphosphine ligand (S,S,S,S)-3 with a cyclobutane backbone has been synthesized in good yield by facile transformations. The asymmetric induction efficiency of these chiral bisphosphine ligands in Pd-catalyzed asymmetric allylic substitution reactions was evaluated. Under the experimental conditions, the allylic substitution products could be obtained in excellent yields (up to 99 %) and enantioselectivities (up to 98.9 % ee). By taking advantage of the high enantioselectivity of this catalytic reaction and the easily derivable carboxylate groups on the cyclobutane backbone of ligand (S,S,S,S)-3, a new type of analogous ligand (S,S,S,S)-4 as well as the MeO-PEG-supported soluble ligand (S,S,S,S)-5 (PEG=polyethylene glycol) have also been synthesized and utilized in asymmetric allylic substitution reactions. In particular, the MeO-PEG supported (S,S,S,S)-5 b had a synergistic effect on the enantioselectivity of the reaction compared with its nonsupported precursor (S,S,S,S)-4 c, affording the corresponding allylation products 14 a and 14 b with excellent enantioselectivities (94.6 and 97.2 % ee, respectively). Moreover, the Pd complex of (S,S,S,S)-5 b could easily be recovered and recycled several times without significant loss of enantioselectivity and activity in the allylic substitution reactions.     

New methodology for tosylation of hydroxylic supports as exemplified by the immobilization of micrococcal endonuclease on agarose

Improvement have been made in a simplified procedure we previously reported (J.Mol.Catal. (1986),38,227 for the activation of tosyl chloride of supports possessing primary hydroxyl groups. The method is simple, can be completed in less than 90 min, yields a broad range of activation degrees, and, since it involves no toxic reagents, may be used for preparing immobilized enzymes to be utilized in food manufacturing and processing. The immobilization ofStophylococcal Nuclease has been carried out by this method. The insolubilized derivatives are more active than the native enzyme in the hydrolysis of DNA. The thermal stability of nuclease derivatives is greater than that of the native enzyme. These derivatives remain active at 50°C, and the native enzyme, 39°C. The insolubilized nuclease is more stable against organic solvents such as, dimethylsulfoxide (DMSO) or tetrahydroduran (THF) than the native enzyme.     

The thermal immobilization of hydroxy-terminated silicone phases in high-temperature-silylated glass capillaries. A study of reaction mechanisms

Differently pretreated glass capillaries were coated with hydroxy-terminated methyl or methyl-phenyl polysiloxane gum phases and cured at 340–360°C for several hours. The volatile reaction products formed during the baking procedure were analyzed and the retention behavior of various polar test compounds were investigated both before and after the heat treatment. The findings were used to establish a reaction scheme which explains crosslinking and surface bonding of hydroxy-terminated silicone phases in high-temperature-silylated glass capillaries. The principle has been extended to the immobilization of common endcapped silicone phases by mixing them with hydroxy-terminated phases.     

聚乙二醇—硝酸镧配位聚合物的表征研究

以聚乙二醇(PEG)为配位体,首次合成了三价稀土金属镧与PEG的配位聚合物。实验测定了该配位聚合物的红外光谱、示差扫描量热谱(DSC)、热失重分析(TGA)和凝胶渗透色谱(GPC),并就配位反应、热分解以及配位前后分子流体力学体积的变化进行了讨论。