相转移催化在高分子化合物合成中的应用

 综述了相转移催化用于高分子化合物合成的主要研究进展．介绍了季铵盐类及冠醚类相转移催化剂在高聚物的亲核取代反应、阴离子开环聚合反应及自由基聚合反应中的应用．重点总结了亲核取代反应中聚苯乙烯类化合物的功能化及化学修饰，包括合成路线、反应机理、温度以及催化剂和溶剂的种类与用量等因素对反应的影响．冠醚类化合物的催化效果略优于季铵盐类化合物，而后者的成本低、毒性小、应用更广泛，其催化的反应应作为今后研究的重点，以期将相转移催化技术尽早用于工业化生产．     

新型开链聚醚胺(Ⅲ)对苯并三唑N-烷基化反应的催化作用

苯并三唑N-取代基衍生物Ⅰ和Ⅱ是一类重要的杂环化合物,苯并三唑的N—H受吸电子基团—N=N—的影响,呈现较弱的酸性(pK_a=8.2)。苯并三唑在强碱作用下生成负离子,然后与烷基化剂反应,得到N-1和N-2-烷     

相转移催化合成增塑剂BBP和水杨醛的研究

相转移催化合成增塑剂ＢＢＰ和水杨醛的研究郭锡坤，高文华，曾东宇（汕头大学化学系，汕头５１５０６３）关键词相转移催化，季铵盐，聚乙二醇，邻苯二甲酸丁苄酯，水杨醛，增塑剂邻苯二甲酸丁苄酯（增塑剂ＢＢＰ）是一种优良的增塑剂．邻羟基苯甲醛（水杨醛）不仅是重要...     

组合化学法筛选聚苯乙烯固载季铵盐相转移催化剂研究(I)

利用组合化学方法合成了一个含有60种不同结构的聚苯乙烯固载季铵盐相转移催化剂的催化剂库,以有外加碱条件下亲核取代反应为探针反应,利用迭代法从中筛选出了活性最高的催化剂,建立了一种快速合成和筛选聚苯乙烯固载季铵盐相转移催化剂的方法。     

肉桂酸的催化氧化反应研究

研究了季铵盐催化下高锰酸钾氧化肉桂酸的反应。考察了催化剂、反应时间、温度、高锰酸钾的用量及反应体系的酸碱性对反应的影响。在优化反应条件下,反应产率可达72.30%。     

A Base‐Free Neutral Phase‐Transfer Reaction System

Although phase‐transfer reactions catalyzed by using quaternary ammonium salts are generally believed to require base additives, we discovered that, even without any base additives, conjugate additions of 3‐substituted oxindoles to nitroolefins proceeded smoothly in the presence of lipophilic quaternary ammonium bromide under water–organic biphasic conditions. The mechanism of this novel base‐free neutral phase‐transfer reaction system is investigated and the assumed catalytic cycle is presented together with interesting effects of water and lipophilicity of the phase‐transfer catalyst. The base‐free neutral phase‐transfer reaction system can be applied to highly enantioselective conjugate addition and aldol reactions under the influence of chiral bifunctional ammonium bromides as key catalysts. The structure of the chiral ammonium enolate intermediate is discussed based on the single‐crystal X‐ray structures of relevant ammonium salts and the importance of bifunctional design of catalyst is clearly explained in the model of intermediate.     

Effect of stoichiometry and diffusion on an epoxy/amine reaction mechanism

The bulk phase kinetics of an epoxy (DGEBA) /amine (DDS) thermoset have been studied using DSC, FTIR, and ¹³C-NMR. In the absence of catalyst, the reaction was found to involve a main exothermic reaction between epoxide and amine hydrogen and a side reaction between tertiary amine formed in the main reaction and epoxide. The main reaction was exothermic while the side reaction had no discernable exotherm. Etherification did not occur to any significant extent. Since only the main reaction is exothermic, DSC was very useful for studying the main reaction kinetics. FTIR was used for determining whether epoxide and amine hydrogen were consumed at different rates as a way of following the side reaction. An IR band previously unused by other investigators was used to monitor the amine hydrogen concentration. NMR confirmed the above mechanism by identifying the formation of a quaternary ammonium ion/alkoxide ion pair as a reaction product of tertiary amine and epoxide. This mechanism has been successfully fit to a rate law valid over the entire extent of reaction. The rate constant for the epoxy/amine addition reaction was found to depend on hydroxide concentration (extent), reaction temperature, and glass transition temperature and included contributions from uncatalyzed and autocatalyzed parts. The side reaction (quaternary ammonium ion formation) formed weak bonds which did not affect the overall system T_g. Both reactions were second order. The rate constants for the main reaction first increase with increasing extent due to autocatalysis by hydroxide before decreasing due to the diffusion limit caused by gelation and vitrification. © 1995 John Wiley & Sons, Inc.     

A NEW PHASE TRANSFER CATALYST AND ITS APPLICATIONS IN ORGANIC TRANSFORMATIONS1*

ABSTRACT

A new quaternary ammonium bromide salt has been used for the first time in phase transfer catalysis (PTC) reactions such as oxidation of alcohols to carbonyl compounds, alkylation and esterification reactions. Improved yields and reduced reaction times have been achieved by this procedure.

     

A HYDROGEN BONDING ASSISTED CATALYST SCREENED OUT VIA COMBINATORIAL CHEMISTRY STRATEGY

1. INTRODUCTIONReduction of organic compounds by NaBH, is often used in organic synthesis. The reactiollis only proceeded in the interface between the organic phase and water phase because of the lowsolubility of NaBH. in organic compounds, and this results in the slow reaction rate and lowyield. In order to increase the reaction rate and yield, NaBH, was converted totetraalkylammonium borohydrides II' 'l, and this made the operating process complex and greatamount of quaternary ammon…     

A HYDROGEN BONDING ASSISTED CATALYST SCREENED OUT VIA COMBINATORIAL CHEMISTRY STRATEGY

Possibilities for enhancement of catalytic reaction rate by combining phase transfer catalysis and hydrogen bonding of the catalyst with the substrate and reagent were studied.A phase transfer catalyst library with sixty polystyrene-supported quaternary ammonium salt catalysts was synthesized.The reduction of acetophenone by NaBH4 was used as the probing reaction to select out the ost active catalyst in the library by using iterative method.which was the gel-type triethanolamine aminsating strongly asic anion exchange resin with the crosslinking degeree of 2% A hydrogen bonding assisted catalytic mechanism was proposed to explain the high catalytic activity of the catalyst.     

Efficient and Convenient Synthesis of Diethers from Furoin Under Ultrasound and Solid-liquid Phase Transfer Catalysis Conditions

Introduction Compounds having an active hydroxy group, such as, acyloins can be easily alkylated by alkyl halides in the presence of a phase transfer catalyst (PTC). The reaction is usually carried out in the presence of concentrated aqueous sodium or potassium hydroxide and a phase transfer catalyst, such as, quaternary ammonium salts[1-3], which facilitate the interphase transfer of species, making reactions between reagents in two immiscible phases possible. The reaction involves a series of equilibrium and mass-transfer steps.     

TS-2微球的形成机理、后处理修饰和催化应用

钛硅分子筛材料是一种优异的选择性氧化反应催化剂,能在温和的条件下活化双氧水,并且只副产水,构建了一系列绿色高效的催化反应体系,已成功地应用于环己酮氨肟化、丙烯环氧化等工业过程.但是,工业上使用的钛硅分子筛通常需要经过成型,这避不可免地引入惰性的粘结剂甚至会造成堵孔,导致催化剂的活性降低.因此,直接合成具有微米尺度的钛硅分子筛材料有望解决上述问题.本文通过控制晶化条件直接水热合成了一种由初级粒子经晶间交叉生长堆积成的TS-2微球,详细考察反应条件,包括季铵盐模板剂的用量、H2O/Si比、醇的存在与否和晶化温度等的影响,发现反应体系保持高的碱度、静态晶化以及体系无醇是TS-2微球形成的关键因素.进一步地对TS-2晶化过程进行详细跟踪考察,发现常规TS-2纳米颗粒与TS-2微球在晶化初期均会形成无定形微球.随着晶化的进行,无定形相晶化成为TS-2纳米晶粒,是一级粒子,相互堆积形成次级粒子.较高的碱度使得TS-2微球的一级粒子以交叉生长的方式堆积,从而保证微球形貌在整个晶化过程中得以保持;而TS-2纳米颗粒中初级粒子以平行的方式堆积,无法保持初始的微球形貌,最终形成纳米尺度的聚集体.扫描电镜和透射电镜照片均证实了TS-2微球中初级粒子成交叉生长的方式堆积.TS-2微球催化剂经模板剂、氯化铵和哌啶组成的混合溶液水热处理,发生了溶解-再晶化过程,外比表面积从148增至176 m2 g-1,介孔孔容从0.16 cm3 g-1升至0.24 cm3 g-1;成功引入介孔的同时,仍能保持TS-2微球形貌以及Ti活性中心的四配位状态.经哌啶混合溶液处理后得到的MS-TS-2-PI在环己酮肟化反应中表现出优于MS-TS-2微球的催化性能,环己酮转化率从18.6%升至91.4%,环己酮肟选择性从86.6%升至97%.再经Na+离子交换可以消除骨架中的Si-OH,增强了骨架的疏水性,进一步地提高了其在环己酮肟化反应中的催化性能;环己酮转化率和环己酮肟选择性均>99%.在环己酮肟化连续反应中,TS-2微球表现出稳定的催化性能,使用寿命达到90 h,与工业TS-1催化剂相当,是一种具有工业前景的催化剂.     

Enantioselective alkylation of beta-keto esters by phase-transfer catalysis using chiral quaternary ammonium salts

Catalytic enantioselective alkylation promoted by a quaternary ammonium salt from cinchonine as a phase transfer catalyst is described. Treatment of cyclo beta-keto esters with alkyl halide under mild reaction conditions afforded the corresponding alpha-alkylated beta-keto esters in moderate to excellent yields with high enantiomeric excesses     

相转移催化法合成RAFT试剂

以苯为有机相,季铵盐为相转移催化剂,二硫代苯甲酸溴化镁分别与溴化苄、2-溴丁酸-2’-羟基乙酯及α-溴乙基苯反应,合成了三种不同结构的RAFT试剂——二硫代苯甲酸酯(3a～3c),收率82.7%～85.5%,其结构经1H NMR和IR确证。     

Kinetics of Reaction Bisphenol-S Epoxy Resin with Methylacrylic Acid

The reaction kinetics of bisphenol-S epoxy resin with methyl-acrylic acid in the presence of quaternary ammonium salt catalyst was studied. The reaction rate constants at different temperatures were determined. The reaction is first order with respect to epoxy group, zero order with respect to methylacrylic acid and 0.71 order with respect to quaternary ammonium salt catalyst, respectively. The mechanism of this reaction was discussed.     

New epoxy-terminated oligoesters: Precursors to totally biodegradable networks

Two types of novel biodegradable epoxy resins, carrying cycloaliphatic-epoxy and glycidyl ester end-groups, have been synthesized from hydroxy-telechelic oligoesters. The cycloaliphatic-epoxy end-groups were based on either methyl cis-4-cyclohexene-2-(carboxylic acid)-1-carboxylate or 3-cyclohexene-1-carboxylic acid. These compounds were reacted with hydroxy-telechelic poly(ε-caprolactone-co-D ,L -lactide) oligoesters, yielding cycloaliphatic-olefin-terminated oligomers. Conversion of the olefin to the epoxide groups was achieved using a phase transfer epoxidation with an inorganic peracid derived from the reaction of phosphoric acid, sodium tungstate, and hydrogen peroxide. Aliquat 336, a quaternary ammonium salt, acted as the phase transfer catalyst. Nearly theoretical conversion of hydroxy to epoxy end-groups was achieved in only one case, however, alternative variations of this method of synthesis show promise. To prepare glycidyl ester-terminated prepolymers, hydroxy-telechelic poly(ε-caprolactone) oligoesters were reacted with succinic anhydride, in 1,2-dichloroethane with 1-methylimidazole as catalyst, resulting in (carboxylic acid)-terminated oligomers. After conversion of the end-groups to the potassium carboxylate salt by titration with methanolic KOH, the isolated salt was dried and reacted with epibromohydrin in acetonitrile at reflux, using an 18-C-6 crown ether as the phase transfer catalyst, thus preparing the (glycidyl ester)-telechelic prepolymer. Epoxide equivalent weights differed by 2.7–7.1% from the theoretical values. These cycloaliphatic-epoxide and glycidyl ester-terminated prepolymers may be crosslinked with anhydrides or amines, respectively, to produce totally bioabsorbable networks. © 1993 John Wiley & Sons, Inc.     

Mild, convenient and efficient synthesis of novel 2,2-dichloro-1,3-diarylaziridines from Schiff bases by phase transfer CTAB catalysis under low concentration alkaline conditions

A mild and efficient method for preparation of novel 2,2-dichloro-1,3-diarylaziridines from Schiff base compounds in the presence of Ar-cetyl-N,N,N-trimethyl ammonium bromide(CTAB) as phase transfer catalyst has been described.The reaction is dramatically enhanced in the presence of quaternary ammonium salt.The corresponding products have been obtained in excellent yields,high purity and short reaction times.     

Chloromethylated polystyrene reaction with tris(2-hydroxyethyl)amine. I. Crosslinked polymers prepared by chloromethylated polystyrene with tris(2-hydroxyethyl)amine

A multifunctional crosslinked polymer resulted from a chloromethylated polystyrene reaction with tris(2-hydroxyethyl)amine. A benzyl chloride reaction (chosen as a structural unit model) with tris(2-hydroxyethyl)amine was investigated to explain the reasons for the crosslinking. Amino-ethers and tris(2-hydroxyethyl)amine hydrochloride in addition to ammonium quaternary salt were isolated from this reaction. The formation of amino-ethers proved that an ammonium quaternary salt rearrangement also takes place during the quaternization reaction. This rearrangement leads to chloromethylated polystyrene during its reaction with tris(2-hydroxyethyl)amine.     

Kinetics of synthesis of bis‐(benzoxazolyl‐2‐methyl) sulfide under phase‐transfer catalysis conditions

Kinetics of synthesis of bis‐(benzoxazolyl‐2‐methyl) sulfide (BBMS) is investigated under phase‐transfer catalysis conditions. Thus, the reaction of 2‐chloromethylbenzoxazole and sodium sulfide is carried out in a two‐phase (organic/water) medium, and quaternary ammonium salt and quaternary phosphonium salt are used as phase‐transfer catalyst (PTC) in the reaction. The conversion of 2‐chloromethylbenzoxazole is dramatically enhanced by adding a small quantity of PTC and is also greatly affected by the reaction conditions. The effects of various reaction variables on the kinetics are investigated, including the amount of catalyst, the temperature, the kinds of catalysts, the kinds of solvents, and the agitation speed. An interfacial reaction mechanism is proposed to explain the characteristics of the reaction. A pseudo‐first‐order rate model is established to describe the relationship between the fractional conversion and the reaction time. The kinetics data demonstrate that the model is suitable to the reaction of synthesis of BBMS. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 296–302, 2009     

The Effect of Iodide Ion in Phase-Transfer Catalytic Syntheses of Benzyl Esters

In order to examine the effect of iodide ions on reaction catalyzed by phase-transfer technique, we made kinetic studies, under the influence of added Na1, on the synthesis of benzyl esters from benzyl chloride and sodium carboxylate. These carboxylates include sodium acetate, sodium benzoate, sodium salicylate and sodium formate; the catalyst was a quaternary ammonium salt. The results reveal that iodide ions at a suitable concentration accelerate the reaction, whereas iodide ions in excess poison the catalyst. The optimum concentration varies with the reaction system. This critical concentration depends upon the distribution coefficient of the intermediates formed in the reactions.