聚氧乙烯类表面活性剂在二氯卡宾制备中的相转移催化作用

聚氧乙烯类表面活性剂可作为制备二氯卡宾时的相转移催化剂,其效能与分子中氧乙烯(EO)单位的数目有关。     

聚氧乙烯类表面活性剂相转移催化性能的研究(Ⅲ)——取代环戊二烯的合成

本文报导了用聚氧乙烯类表面活性剂作为相转移催化剂,以环戊二烯与卤代烷反应合成烷基取代环戊二烯的方法。反应在固-液相条件下进行,其难易程度取决于卤代垸的反应活性。以该法合成了九个烷基取代环戊二烯衍生物。     

香茅基芳基醚类保幼激素类似物的简便合成方法

许多香叶基芳基醚和香茅基芳基醚已证明是有效的昆虫保幼激素^[1-3].以往合成此类化合物,只能在酚与较活泼的香叶基溴的反应中使用KOH(或NaOH),与较不活泼的香茅基溴的反应则仍沿用Williamson法.我们曾报导了以聚氧乙烯类表面活性剂代替冠醚作为相转移催化剂合成醚类化合物的方法^[4].     

2H NMR研究嵌段共聚物溶致液晶相的结构演化与水分子动力学行为

采用2H NMR实验结合谱图线型的理论模拟方法研究了两亲性嵌段共聚物聚氧乙烯一聚氧丙烯一聚氧乙烯／氘代水／对二甲苯三元体系形成的不同液晶相的结构演化和水分子动力学行为．结果表明,对不同组分浓度的样品,2H谱线型发生明显的变化,对应体系从各向同性相、六角相和层状相间的系列结构转变．通过NMR弛豫模型获得了液晶相结构演化中序参数和分子运动相关时间的变化规律,理论模拟获得的自旋．晶格弛豫时间T1、自旋-自旋弛豫时乃等水分子动力学参数与实验测量结果吻合．结果表明：层状相四极劈裂及序参数随嵌段共聚物或二甲苯含量的增加呈现一个极大值,水分子的兀随着嵌段共聚物浓度增加而明显减小,而疋在六角相到层状相的转变中发生了明显的变化．研究表明,通过理论模拟2HNMR实验获得的谱图线型是研究液晶相结构演化和动力学的有力工具．     

温控相转移膦配体与催化(Ⅺ):OPGPPRh催化的两相高碳烯烃的氢甲酰化反应

一种连由辛基脂肪醇聚氧乙烯基团的邻苯二酚亚磷酸酯新型水溶性膦配体(OPGPP)与铑原位形成的催化剂应用于高碳烯烃的两相氢甲酰化反应。获得了99.3%的烯烃转化率和97.3%醛收率,催化剂表现很高的活性且催化剂可以回收使用。     

微波场中二氯卡宾产生的研究

二氯卡宾是应用最为广泛的活性中间体,早期制备二氯卡宾的方法为氯仿与叔丁醇钾等强碱作用,条件苛刻。一直到1969年Makosza和Wawrzyniewicz的著名论文发表后,用强碱水溶液和相转移催化剂制取二氯卡宾被认为是最简捷的方法。另据文献报道,以聚氧乙烯类表面活性剂作催化剂进行固-液相反应制备二氯卡宾也可获得较理想的结果。但广泛的实     

相转移催化反应研究__二卤卡宾加成反应

自从Makosza等发现鎓翁盐化合物作为相转移催化剂以来,十余年来相转移催化(PTC)已广泛应用于有机合成领域。Dehmlow等对相转移催化剂的催化效率及二氯卡宾与脂肪烯烃反应的动力学作过一些探讨。     

Ⅰ.新的2-取代环戊-2-烯酮的合成和茉莉酮类化合物的合成 Ⅱ.钩吻素子合成的研究

在第一部份的工作中,作者发现了一条新的2-取代环戊-2-烯酮的合成路线。自环戊二烯出发,以聚氧乙烯类衍生物为相转移催化剂,固体氢氧化钾为碱,制得一系列取代环戊二烯;将烷基取代环戊二烯在甲醇溶液中与溴加成后接着酸性水解,得到纯度为95％以上的2-取代环戊-2-烯酮。检测并讨论了反应中间体和产物的生成机理,对戊基取代环戊二烯的     

聚合物支载的有机催化剂Ⅰ.非手性有机催化剂

对二十余年来聚合物支载的有机催化剂的合成、性能及其在催化反应中的应用,包括负载催化剂的回收和重复使用等进行了综述.用于支载体的聚合物包括交联聚合物、线型聚合物及树形聚合物;支载的有机催化剂包括手性及非手性催化剂两类.本文作为第一部分将介绍聚合物支载的非手性有机催化剂,包括相转移催化剂、氧化催化剂、酸以及碱催化剂.     

新型非离子表面活性剂的合成与表征

环氧化合物;新型非离子表面活性剂的合成与表征;疏水间隔链;聚氧乙烯     

Aqueous to Organic Phase Transfer of Au25 Clusters

Aqueous to organic phase transfer of water soluble sub-nanocluster, Au₂₅SG₁₈ (-SG, glutathione thiolate) is demonstrated using the phase transfer reagent, tetraoctylammonium bromide. The phase transfer occurred by the electrostatic attraction between the hydrophilic carboxylate anion of the glutathione ligand on the cluster surface in the aqueous phase and the hydrophobic tetraoctylammonium cation in the toluene phase. Detailed spectroscopic characterization of the phase transferred cluster using optical absorption, photoluminescence and X-ray photoelectron spectroscopy showed that the cluster retains its integrity during the phase transfer. The interaction of the cluster with the phase transfer reagent can be studied with infrared spectroscopy. The phase transferred cluster can be dried and redissolved in an organic medium, just as the original cluster. This is the first report of the phase transfer of a sub-nanocluster, keeping the cluster core intact. The effect of dilution and pH on phase transfer of this cluster is studied in detail. This method promises several possibilities to explore the properties, reactivity and applications of sub-nanoclusters both in the aqueous and organic phases. Dedicated to Prof. C.N.R. Rao on his 75th birthday, whose work on phase transfer of nanoparticles has inspired this work.     

Using Aggregation to Chaperone Nanoparticles Across Fluid Interfaces

Nanoparticles (NPs) transfer is usually induced by adding ligands to modify NP surfaces, but aggregation of NPs oftentimes hampers the transfer. Here, we show that aggregation during NP phase transfer does not necessarily result in transfer failure. Using a model system comprising gold NPs and amphiphilic polymers, we demonstrate an unusual mechanism by which NPs can undergo phase transfer from the aqueous phase to the organic phase via a single-aggregation-single pathway. Our discovery challenges the conventional idea that aggregation inhibits NP transfer and provides an unexpected pathway for transferring larger-sized NPs (>20 nm). The charged amphiphilic polymers effectively act as chaperons for the NP transfer and offer a unique way to manipulate the dispersion and distribution of NPs in two immiscible liquids. Moreover, by intentionally jamming the NP-polymer assembly at the liquid/liquid interface, the transfer process can be inhibited.     

Polyarylates. V. The influence of phase transfer agents on the interfacial polycondensation

The effect of various phase transfer agents on the interfacial polycondensation of bisphenol A with isophthaloyl chloride was investigated. It was found that the transfer rate of bisphenolate and, thus, the reaction rate of polycondensation were increased with an increasing lipophilicity of the phase transfer agent, i.e. TBAC > TEBAC > TEAC, whereas the equilibrium of bisphenolate between the organic phase and the aqueous phase was hardly affected. Moreover, experimental evidence indicated that a phase transfer agent of high lipophilicity reduced the hydrolysis of the acid chloride, an important aspect in interfacial polycondensation.     

Stimuli-triggered phase transfer of polymer-inorganic hybrid hairy particles between two immiscible liquid phases

Polymer brush-grafted particles (i.e., hairy particles) capable of undergoing direct, especially reversible, phase transfer from one liquid phase to another immiscible liquid phase in response to environmental changes have received growing interest due to their great potential in a wide variety of applications. This article is intended to review recent exciting advances in stimuli-triggered phase transfer of hairy particles in liquid-liquid biphasic systems. We start with a discussion of the mechanism of particle transfer across a liquid-liquid interface and progress to the synthesis of polymer brushes grafted on particles and the transfer of hairy particles between two immiscible liquid phases induced by various external stimuli, including temperature, pH, ionic strength, light, and solvents. The applications of thermally triggered phase transfer of hairy particles in catalysis (thermoregulated phase transfer catalysis) are discussed, followed by a summary and our perspective on future development. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1600–1619     

2,2′联吡啶在水/硝基苯界面对Co(Ⅱ)的相转移催化

循环伏安法研究表明2,2′-联吡啶催化Co(Ⅱ)通过水/硝基苯界面的相转移伴有化学反应发生。水相或有机相的伴随化学反应直接影响Co(Ⅱ)与2,2′-联吡啶逐级配合物的相转移的循环伏安行为,并观察到类似于金属电极/电解质溶液界面出现的不可逆渡,不同的配合物,相转移机制不同。     

Electrochemically driven transfer of carboxyl-terminated PAMAM dendrimers at the water/dichloroethane interface

The transfer of PAMAM dendrimers bearing carboxylic acid peripheral groups between two immiscible liquids was studied by means of the three phase junction system, using a gold wire vertically crossing the interface and decamethyl ferrocene as the redox probe in the organic phase. While the voltammetric behavior indicates kinetic limitations of the overall ion–electron transfer process, thermodynamic data shows that the phase transfer process is entropically controlled. Four dendrimer generations were analyzed and it was found that the kinetics as well as the thermodynamics of the phase transfer reaction are size dependent.     

Catalytic investigations of calix[4]arene scaffold based phase transfer catalyst

Calix[4]arene scaffold based quaternary ammonium salts as multi-site phase transfer catalysts were prepared and their catalytic activities were investigated for Darzens condensation, O/N-alkylation reactions and ethyl benzene oxidation. These calix[4]arene based multi-site phase transfer catalysts showed significant high catalytic activity as compared to single-site phase transfer catalysts.     

Design of Binaphthyl‐Modified Symmetrical Chiral Phase‐Transfer Catalysts: Substituent Effect of 4,4′,6,6′‐Positions of Binaphthyl Rings in the Asymmetric Alkylation of a Glycine Derivative

A series of symmetrical chiral phase‐transfer catalysts with 4,4′,6,6′‐tetrasubstituted binaphthyl units have been designed, and these aryl‐ and trialkylsilyl‐substituted phase‐transfer catalysts, which included a highly fluorinated catalyst, were prepared. The chiral efficiency of these chiral phase‐transfer catalysts was investigated in the asymmetric alkylation of tert‐butylglycinate–benzophenone Schiff base under mild phase‐transfer conditions, and the eminent substituent effect of the 4,4′,6,6′‐positions of the binaphthyl units on enantioselection was observed. In particular, the OctMe₂Si‐substituted catalyst was found to be highly efficient for the phase‐transfer alkylation of tert‐butylglycinate–benzophenone Schiff base with various alkyl halides, including sec‐alkyl halides. The highly fluorinated catalyst was also utilized as a recyclable chiral phase‐transfer catalyst by simple extraction with fluorous solvents.     

A general and reversible phase transfer strategy enabling nucleotides modified high-quality water-soluble nanocrystals

We report a facile and general phase transfer strategy using nucleotides or nucleosides as phase transfer reagents to render a wide variety of nanomaterials transferring from organic phase to aqueous phase or vice versa, while preserving their intrinsic physicochemical features.     

Phase transfer catalytic system with the third liquid phase

Phase transfer catalysis, a technique to bring the reactants in two immiscible phases together by adding a phase transfer agent, has been employed in the production of fine chemicals and pharmaceuticals in the last few decades. The third liquid phase (catalytic phase) may be formed when phase transfer catalysts (PTC), cannot be dissolved in either organic or aqueous phase. The third phase catalytic systems have the following three advantages, that is, (1) high activity (2) repeated use and (3) separation between the organic phase and the aqueous phase. It is expected that simple new processes can be constructed by applying these three advantages.