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31.
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A palldium(0)-catalyzed tandem cyclization/Suzuki coupling reaction of various 1,6-enyne substrates was developed. This Pd-catalyzed enyne cyclization reaction represents a new process for the synthesis of stereodefined alpha-arylmethylene-gamma-butyrolactones, lactams, multifunctional tetrahydrofurans, pyrrolidines, and cyclopentanes. The mechanism of the reaction was studied by the employment of different enyne isomers and boronic acids; a pi-allyl palladium intermediate was suggested to explain the formation of the cyclic products. The stereochemistry of this reaction can be well explained by a chairlike transition state. 相似文献
33.
本文介绍水杨配合与4-氨基-3,5-二乙基-1,2,4-三唑缩合而成对称三唑Schif碱(SAETZ)与氯化铜(CuCl2)形成一种新的配合物Cu(SAETZ)2(SAETZ=4-(邻羟苯基亚甲基)-亚胺-3,5-二乙基-1,2,4-三唑)。配合物的晶体结构表明,分子中两个偶氮甲碱的N原子及两个酚氧原子与中心Cu原子形成规则的平面配位结构。晶体属单斜晶系,空间群P21/n,a=8.688(2),b=9.314(1),c=16.515(4),β=94.34(2)。,V=1332.5(7)3,Z=2。 相似文献
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Initiation mechanism of the photopolymerization of acrylonitrile and methyl methacrylate, usingbinary condensed aromatic hydrocarbon (CAH)-aniline systems as initiator, was studied. The strongerthe electron-donating ability of the aniline derivatives, the faster the the of photopolymerizationwill be. The radical intermediates produced by photoreaction between anthracene and anilinewere detected with ESR spectra. The initiation scheme involves the formation of exciplex betweenthe excited singlet state of CAH and the ground state of aniline as the first step, and then followedby proton transfer, leading to the generation of two kinds of radicals. From the end-group analysisof the polymers obtained, it is suggested that both kinds of radicals are involved in the initiation. 相似文献
36.
Recent progress in combinatorial chemistry and parallel synthesis has radically changed the approach to drug discovery in the pharmaceutical industry. At present, thousands of compounds can be made in a short period, creating a need for fast and effective in silico methods to select the most promising lead candidates. Decision forest is a novel pattern recognition method, which combines the results of multiple distinct but comparable decision tree models to reach a consensus prediction. In this article, a decision forest model was developed using a structurally diverse training data set containing 232 compounds whose estrogen receptor binding activity was tested at the U.S. Food and Drug Administration (FDA)'s National Center for Toxicological Research (NCTR). The model was subsequently validated using a test data set of 463 compounds selected from the literature, and then applied to a large data set with 57,145 compounds as a screening example. The results show that the decision forest method is a fast, reliable and effective in silico approach, which could be useful in drug discovery. 相似文献
37.
提出用两个热流变简单粘弹体的并联体系作为两相聚合物的粘弹模型,将先前的动态力学温度谱分析方法推广到两相聚合物中去.运用这种新方法从动态力学数据求出了PET/70PHB共聚物的双活化能,其中150℃左右的转变活化能为71.9kcal/mol,70℃左右的转变活化能为117.5koal/mol,这一数值与文献上PET/60PHB这个转变的活化能120kcal/mol相接近.文中还计算了共聚物在不同温度下的10s应力松弛模量,所得结果与实测值相吻合. 相似文献
38.
Chen Xiao-Ming Wu Yu-Luan Tong Ye-Xiang Sun Ziming David N. Hendrickson 《Polyhedron》1997,16(24):1041
A novel tetranuclear terbium(III) complex [Tb4(OH)4(pybet)6(H2O)8][Tb4(OH)4(pybet)6(H2O)7 (NO3)](ClO4)14·6H2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb4(μ3-OH)4(μ2-carboxylato-O,O′)6 core. The ligand pybet is pyridinoacetate, C5H5+N-CH2CO2−. Magnetic susceptibility data were measured for this Tb4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = −0.015 cm−1) or there is a small crystal-field splitting of the 7F6 TbIII ground state. 相似文献
39.
Effect of multi-walled carbon nanotubes on non-isothermal crystallization kinetics of polyamide 6 总被引:2,自引:0,他引:2
The non-isothermal crystallization behaviors of multi-walled carbon nanotubes (MWNTs)/polyamide 6 (PA6) composites were investigated by differential scanning calorimetry (DSC). Three methods, namely, Avrami, Ozawa and Mo, were carried out to analyze the non-isothermal crystallization data. The results showed that the MWNTs in PA6 acted as effective nucleation agents. However the crystallization rate of composites obtained was lower than that of the neat PA6. It is indicated that the presence of MWNTs influenced the mechanism of nucleation and the growth of PA6 crystallites. 相似文献
40.