有机催化基团转移聚合的研究进展

基团转移聚合是20世纪80年代继活性阴离子聚合之后由杜邦公司所开发的一种针对丙烯酸衍生类单体的活性聚合方法.其中,丙烯酸衍生类单体主要包括丙烯酸酯、甲基丙烯酸酯、丙烯酰胺及丙烯腈四大类.基团转移聚合中的链引发与链增长基元反应均为向山-迈克尔加成反应.因此,反应原理上而言碱和酸均可成为该聚合反应的催化剂.在有机小分子催化剂被应用于该聚合方法之前,所用的碱为含立体位阻阳离子的可溶性离子化合物,其中亲核性的阴离子起到催化剂的作用;所用的酸为具有路易斯酸性的金属或过渡金属化合物.2007年以来,有机小分子碱和酸逐渐被应用于基团转移聚合的催化剂,并把该类聚合称为有机催化基团转移聚合.相较于以往的基团转移聚合,有机催化基团转移聚合在聚合物分子量及分子量分布控制、可聚单体的范围、聚合物拓扑结构的控制等方面都有了全新的拓展.本综述主要围绕我们近年来在该领域的工作,从有机强碱催化的基团转移聚合、有机强酸催化的基团转移聚合、基于氢硅烷的新型有机催化基团转移聚合以及聚合机理4个方面对有机催化基团转移聚合领域的最新进展进行论述.     

甲基丙烯酸酯的基团转移嵌段共聚研究

甲基丙烯酸酯的基团转移嵌段共聚研究戴李宗邹友思陈良坦潘容华（厦门大学化学系厦门３６１００５）关键词基团转移聚合，甲基丙烯酸酯，嵌段共聚物，结构表征基团转移聚合［１］（ＧｒｏｕｐＴｒａｎｓｆｅｒＰｏｌｙｍｅｒｉｚａｔｉｏｎ，ＧＴＰ）具有活性聚合的特点...     

用硅烯醚型引发剂进行的基团转移聚合

本文报道了一类硅烯醚型的基团转移聚合引发剂。并以负离子和HgI_2等为催化剂,进行了甲基丙烯酸酯和丙烯酸酯的基团转移聚合。得到了实测分子量和理论分子量相近且分散性较小的浆合物。进行了甲基丙烯酸甲酯的活性聚合以及其与丙烯酸酯的A-B-A型三嵌段共聚,证实具有活性高分子的特征。探讨了该类引发剂引发基团转移聚合的机理,研究了催化剂和引发剂的配合选择性以及催化剂和引发剂的摩尔比对产物分子量和转化率的影响,发现该类引发剂引发的基团转移聚合是一恒速聚合反应。     

三苯基膦和三甲基氯硅烷直接引发丙烯酸乙酯的基团转移聚合研究

在催化剂溴化锌存在下 ,三苯基膦和三甲基氯硅烷用于直接引发丙烯酸乙酯的基团转移聚合 ,得到了含三苯基膦端基的聚丙烯酸乙酯 ,在这样的聚合系统中能容易地实施丙烯酸乙酯的基团转移聚合反应。动力学研究发现 :终止反应在很大程度上取决于催化剂溴化锌的浓度 ,因此 ,在此基团转移聚合反应中催化剂溴化锌的最有效浓度是丙烯酸乙酯的摩尔浓度的 12～ 16%。由于四价的三苯膦基团引入到所生成的烯酮硅基缩醛 (引发剂 )上 ,聚合的终止反应主要是经过膦叶立德中间体 ,活性端基烯酮硅基缩醛异构化成为无基团转移聚合活性的含碳硅键化合物。     

甲基丙烯酸C_7～C_9酯的基闭转移聚合

研究了甲基丙烯酸Ｃ_７～Ｃ_９酯的基团转移聚合。聚合必须在８０℃以上进行，讨论了聚合条件对聚合速率、分子量、分散性及转化率的影响。     

基团转移聚合的动力学研究

<正> 作为一种新的极性单体加聚方式的基团转移聚合(Group Transfer Polymerization,GTP),近年来发展很快。对不同引发体系和单体的基团转移聚合进行动力学研究,由此得到规律性的认识,明确聚合过程的影响因素,有利于聚合机理的完善。文献已报道了用     

甲基丙烯酸长链烷基酯的基团转移聚合研究

进行了甲基丙烯酸长链烷基酯（庚、辛、壬酯的混合物）的基团转移聚合．得到了具有较高分子量和转化率．分子量分布较窄的聚合产物．研究了聚合条件对产物的分子量及分布，转化率，聚合速率的影响．探讨了聚合反应动力学．认为聚合体系的非极性不利于催化剂的离解，单体较大的空间障碍使扩散困难．均是表观活化能升高和转化难以完全的原因．发现此类单体的基团转移聚合对温度的依赖性极大，本体聚合无自加速现象，容易得到较高的分子量．     

催化剂对基团转移聚合的影响

本文研究了催化剂的种类和用量对硅烯醚型引发剂引发的基团转移聚合的影响。发现四丁基二苯甲酸氢铵(Bu_4NH(C_6H_5CO_2)_2,TBABB)和HsI_2的催化效果较好。只需引发剂的4％的HgI_2即可使MMA的基团转移聚合达到完全转化。认为有效的氧负离子催化剂应由较稳定的铵正离子和电负性较大的氧负离子所组成。过量的催化剂不利于基团转移聚合的进行。考察了TBABB催化剂对温度的依赖性及其浓度对聚合速率,分子量和分子量分布,转化率的影响。     

基团转移嵌段共聚规律研究

基团转移嵌段共聚规律研究夏海平，丁马太，陈萍，郭舰，刘昆棱（厦门大学化学系，３６１００５）基团转移聚合（ＧＴＰ）￣［１］是８０年代出现的新型聚合方法。常用的ＧＴＰ单体主要有三类：甲基丙烯酸酯类、丙烯酸酯类及丙烯腈。由于ＧＴＰ能使某些单体在室温下进行“...     

大分子单体及其规整接枝共聚物

论述了通过活性阴离子聚合、活性阳离子聚合、基团转移聚合、自由基聚合、缩聚等途径合成各种大分子单体,论讨了大分子单体的表征,并结合自己的工作综合介绍近年来大分子单体共聚的进展及其规整接枝共聚物的纯化和特性。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.