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单环戊二烯基镍化合物催化α-硅氢加成反应 总被引:2,自引:0,他引:2
单环戊二烯基镍化合物催化α-硅氢加成反应娄兆文(湖北大学化学系,武汉430062)张伦(武汉大学化学系,武汉430072)关键词有机镍化合物,催化,硅氢化加成。1.前言硅氢化合物对烯烃的加成反应通常必需使用氯铂酸等铂、钯、铑化合物作催化剂[1,2],... 相似文献
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本文介绍O,O-二烷基氢膦酸酯中发生在σ ̄4λ ̄P─H或σ ̄3λ ̄3P─OH键上的几类重要反应如烷基化反应、加成反应、Atherton-Todd反应等,以及这些反应在有机合成中的应用,并对某些新颖反应机理作初步探讨。 相似文献
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含氢甲基硅油含氢量的质谱法测定 总被引:1,自引:0,他引:1
含氢甲基硅油是高分子量的多聚物,用质谱方法对其Si-H键上的氢含量的测定,仅用测定其分子量的办法不易实现。实验中发现,用其两个碎片离子SiO9CH3)2和SiO-HCH^+3作为代表性离子,以它们的丰度比定出甲基含氢硅油的含氢量「H」。结果与用化学方法所测值十分接近。 相似文献
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以丙烯酸和1,3,5,7-四甲基环四硅氧烷(D4H)等为初始原料,经酯化、硅氢加成反应制得1,3,5,7-四(三甲基硅氧羰丙基)-1,3,5,7-四甲基环四硅氧烷(2),水解2制得1,3,5,7-四羧丙基-1,3,5,7-四甲基环四硅氧烷(3),3经Staudinger反应和Curtius重排反应制得1,3,5,7-四异氰氧基乙基-1,3,5,7-四甲基环四硅氧烷(4).反应总收率为14.5%,化合物结构经1H NMR,29Si NMR,IR,MS和HRMS确证. 相似文献
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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. 相似文献
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We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure. 相似文献
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利用元胞动力学方法在二维情况下对浓度、取向序参量的含时Ginzberg-Landau方程进行数值求解,研究了液晶聚合物/柔性链聚合物共混体系的相分离动力学,考察了浓度、取向有序过程的耦合对相分离形态的影响.结果表明,此耦合作用对相分离的时间进程以及相分离图样的空间排布都有影响.液晶聚合物的取向有序相当于增加了两组分间的不相容性而促进两相分离;两个序参量在热力学方面的耦合使液晶聚合物趋向于沿着界面方向取向,而动力学方面的耦合使液晶聚合物分子沿着其取向方向扩散,相分离图样的空间排布由这两种效应共同决定通过极化率张量的定义用数值方法模拟得到了相分离体系的小角光散射图样,结果表明,散射强度分布具有方位角依赖性,它是由浓度、取向序参量的空间变化共同决定的. 相似文献
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The applicability of the method of Giese to the measurement of the influence of monomer reactivity is examined. The reaction of alkyl mercuric salts with sodium borohydride permits the production of alkyl (cyclohexyl and butyl) radicals. Since hydrogen radicals are present in high concentration, the addition of alkenes to the reaction mixture leads to radicals from the alkenes. Further addition of alkene (polymerization) can be nearly completely excluded in this way. The composition of the reaction products is determined by gas chromatography. The addition rate of the alkenes relative to styrene allows correlation with the e value of the Q-e scheme of Alfrey and Price. The method answers the question of how far addition of the monomer complex occurs in one step or as separate addition of both monomers during copolymerization in the presence of charge-transfer (CT) complexes of the monomers. The investigations are performed by using the styrene/acrylonitrile/ZnCl2system, and it is demonstrated that the reactivity of the complexed 相似文献
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Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given. 相似文献
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周小清 《化学物理学报(中文版)》2003,16(2):113-116
基于偶极近似,运用电极化方法,定量研究了电流变液中悬浮颗粒在外电场作用下其体积和形状的变化,并计算了其体积和形状的相对变化率.研究结果表明:悬浮颗粒的体积和形状的相对变化率均与电场强度的平方成正比,并与ER本身的性质有关.一般情况下,颗粒的体积和形状的相对变化率分别为8.4%和12.5%,对总体积变化率的贡献为1.68%.这种变化对于ER系统的电涨和电热都作出了贡献,仅当将颗粒当作刚性球时,其自由能才与电场强度的平方成正比. 相似文献
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A NOVEL APPROACH TO RHEOLOGICAL CHARACTERIZATION FOR THE GELATION IN POLYMER CRYSTALLIZATION 总被引:5,自引:0,他引:5
QingChen Yu-runFan QiangZheng 《高分子科学》2005,(4):423-434
The isothermal crystallizations of three kinds of commercial isotactic polypropylene have been studied by DSC and rheometric experiments, in a range of temperatures where the rate of crystallization is moderate. As the crystallization proceeds, volume contraction induces tensile force upon the parallel plates. The tensile force relaxed quickly in liquid states,but after a critical amount of the relative crystallinity, it starts to accumulate in the static test, that is, with the motionless parallel plates. A new method to determine the liquid-solid transition by the static tensile force is proposed and compared with two dynamic methods of detecting liquid-solid transition, that is, the power-law modulus theory and the yield modulus model. The tensile force method predicted considerably earlier transition than the dynamic methods, and the corresponding DSC data indicate relative crystallinity of larger than 0.2 at the transition times. The limitation of dynamic methods and other possible errors have been analyzed. While the dynamic methods are suitable for slow crystallization, the tensile force method is more appropriate for the crystallization of moderate rates. Moreover, it has the advantage of almost not disturbing the crystallizing materials before the transition. 相似文献
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S. Havriliak Jr 《Colloid and polymer science》1990,268(5):426-439
The dielectric relaxation data of Ishida et al. on a number of acrylic polymers are represented in terms of the relaxation function proposed by Havriliak and Negami using the multi-response techniques developed by Havriliak and Watts. Two of the parameters of this function are interpreted in terms of a temperature dependent distribution of relaxation times. In this method of interpretation the breadth of the distribution function is temperature-dependent while the skewness is not. The temperature dependence of the breadth of the distribution function is similar for most of these acrylic polymers.The parameters of the relaxation function are also interpreted in terms of Mansfield's model which represents intra- and inter-molecular interactions in terms of springs and dash pots. Briefly, increasing the side chain length for the methacrylate series increases the inter-molecular relaxation time which may be due to an increase in the entropy of activation for the orientation process. The difference between the one acrylate in this study and the four methacrylates of the series is a reduction in the intra-molecular relaxation time, apparently due to the lack of the alpha methyl group. 相似文献
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SUO Kai-Nan ZHANG Wei-Lian LI Jian ZHAO Jia-Peng ZHOU Zi-Peng 《结构化学》2007,26(10):1247-1251
In order to discuss the application possibility of SiGe crystal in thermoelectric materials,we investigated the thermoelectric properties of several silicon-germanium alloys with different content,orientation and electric conductive type. As discussed in the experiment result,the absolute value of Seebeck coefficient fluctuates from 300 to 600 μV/K in the whole temperature range. In the present paper,the relationship of Seebeck coefficient against content,orientation and electric conductive type is summarized in detail. The Seebeck coefficient of the sample with <111> orientation is smaller than that in <100> at the same temperature. Absolute value of P-type is larger than that of N-type except pure Ge. But as the temperature increases,the absolute value of pure Ge decreases many times as quickly as that of other specimens. In addition,the specimens of bulk GeSi alloy crystals for experiment were grown by the Czochralski method through varying the pulling rate during the growing process. 相似文献
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The effect of temperature on the solubility of ionic surfactants was interpreted in terms of standard enthalpy and entropy of dissolution at reference temperature by considering the change in the heat capacity. The significant value of the latter quantity causes the curvature of the function logarithm of equilibrium constant (or solubility) vs. the reciprocal thermodynamic temperature. The solubility data for several sodium n-alkylsulfonates, published by Saito, Moroi, and Matuura, were interpreted by nonlinear regression analysis. It was found that both the enthalpy and entropy of dissolution decrease with the chain length. The heat capacity increases in the course of the dissolution process. 相似文献