相转移催化的亲核取代反应

本文论述了相转移催化反应中的亲核取代反应,包括两个部分:1.相转移亲核取代反应在有机合成中的应用;2.相转移催化的亲核取代反应原理。     

有机胂化合物的研究

报道了溴化α－呋喃亚甲基三苯的合成及其与芳醛、酮的相转移催化反应，获得高产率立体专一性的烯烃衍生物。     

三相催化合成苄酯

本文是用季铵盐类相转移催化剂连接到二乙烯基苯交联的聚苯乙烯上,形成不溶性的固体高分子相转移催化剂,应用这种固体催化剂于水和甲苯体系中,三相反应成功地合成了三种苄酯。这种三相催化反应比经典合成方法,具有条件温和,操作简单,更主要的能回收催化剂,经再生处理后能重复使用,再生率是满意的。 反应结果及对产物熔、沸点、红外光谱的测定表明:三相催化合成苄酯是一种行之有效的有机合成新方法。     

相转移催化反应的一般原理

本文讨论子相转移催化反应的一般原理,介绍了相转移催化剂的种类,并以季铵化合物为例,就催化剂结构和催化活性间的关系进行了一般性综述。     

相转移催化

七十年代初发展起来一种异相反应的新理论和方法被Starks称之为相转移催化,它一问世就显示出了强大的生命力。本文着重介绍关于相转移催化一般原理和应用,并给出了应用硬软酸碱规则设计相转移催化反应实例。一、相转移催化的基本原理首先,让我们看一个实验事例:1-氯辛烷与异相的氰化钠水溶液一起加热,在两星期内不发生反应,但若在两相中加入季鏻盐时,反应可在较短时间内完成,并获得高产率的产品。     

相转移催化反应机理与催化剂的结构

针对不同反应物液／液相相转移催化反应机理，总结了不同介质条件下所遵循的机理模式以及该模式下相转移催化反应对催化剂结构的不同要求。     

相转移催化反应在有机合成中的应用

综述了利用相转移催化反应合成新型的植物生长调节剂及其生物活性研究的进展．     

微乳介质中相转移催化制备乙酸苄酯的研究

在Oil/Water(简称O/W)型微乳介质中实施苄氯与乙酸钠的相转移催化反应,在室温下成功地制得了乙酸苄酯,并且研究了几种因素对产品得率的影响,使产品得率可达80%.表明在微乳介质中可大大提高相转移催化效率,从而大大加快反应速率.     

聚氧乙烯类表面活性剂相转移催化性能的研究(Ⅳ)——在Horner-Emmons反应中的应用

前文我们曾先后报导了以聚氧乙烯类表面活性剂代替价昂有毒、制备困难的冠醚作为相转移催化剂在二氯卡宾的制备,醚类化合物的合成以及烷基取代环戊二烯的合成中的应用.在上述应用中均获得了很好的效果.表明聚氧乙烯类表面活性剂具有良好的相转移催化性能,是取代冠醚作为有机合成中相转移催化剂的较理想的替代物,有着很好的应用前景. 继Wittig反应之后,Horner-Emmons反应作为其改良方法在各类烯烃的合成中得到了广泛的应用.近年来,将相转移催化技术应用于该反应已有不少文献报导,但     

相转移催化丁烯水合制仲丁醇工艺研究

结合计算机模拟，实验筛选出适合丁烯水合反应的相转移催化剂（PTC）．进行了工艺研究，考查了在PTC存在下，各主要操作参数对丁烯水合反应的影响，确定了聚乙二醇类的PTC-05为适合该反应体系的最佳PTC．研究表明，PTC-05的加入在较高的温度和水烯比、较低的空速及适量百分比下，可以显著提高丁烯水合的单程转化率，同时对相转移催化反应动力学及机理进行了初步研究．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the