二氧化碳与环氧化物共聚催化剂研究进展

二氧化碳是主要的温室气体,也是最丰富的C1资源.利用二氧化碳与环氧化物共聚生成可生物降解的聚碳酸酯是目前研究的热点之一.就目前的研究情况而言,二氧化碳与环氧化物共聚反应存在的主要问题是催化效率低、催化剂成本高、反应条件苛刻、共聚物产率较低以及催化剂分离复杂等.我们分类综述了二氧化碳与环氧化物共聚的新型催化体系,并探讨了各类催化体系的优缺点,对二氧化碳的资源化利用具有重要的应用价值.     

Fe—Al配位催化环氧丙烷均聚

用于环氧丙烷开环聚合的催化剂为有机金属化合物和稀土络合物等,在对于铁系催化剂催化丁二烯聚合、马来酸酐与苯乙烯共聚和邻苯二甲酸酐与环氧丙烷共聚的研究基础上,我们首次将这一类催化剂用于环氧化物的开环均聚上,发现Fe(acac)3-Al(i-Bu）3催化剂具有良好的催化活性,并进行了产物结构和反应动力学的研究,结构分析表明Fe(acac)3-Al(i-Bu）3催化剂体系具有良好的立体定向性。     

二氧化碳与环氧化物的调节共聚合反应速率

在二氧化碳和环氧化物共聚时加入特定的调节剂，生成有规定的分子量和端基官能度的产物．这种调节聚合的本质是调节剂所含活泼氢与活性中心之间的链转移反应．根据建议的历程，提出了调节共聚速率方程，计算结果与实验一致．     

双金属氰化络合物及其催化的聚合反应

本文综述了双金属氰化络合物及其催化的环氧化物参与的聚合反应研究。双金属氰化络合物是由其内界金属M^Ⅱ通过氰基与外界金属M^Ⅰ连接形成的含 M^Ⅱ-C≡N-M^Ⅰ 桥键的三维网络状无机高分子(M^Ⅰ一般为Zn²⁺、Fe²⁺、Co²⁺和Ni²⁺等二价金属离子,M^Ⅱ一般为Fe²⁺、Fe³⁺、Co²⁺、Co³⁺和Ni²⁺等过渡金属离子)。外界金属M^Ⅰ一般被认为是催化反应的活性中心金属。该类催化剂早期被用于催化环氧化物开环聚合,并逐步发展成为合成中高分子量、低不饱和度聚醚多元醇的极高效催化剂。近年来该类催化剂被用来催化环氧化物/环状酸酐共聚、环氧化物/CX₂(X≡O,S)共聚和环氧化物/环状酸酐/CO₂三元共聚反应合成聚酯、聚碳酸酯、聚(醚-碳酸酯)、聚硫代碳酸酯和聚(碳酸酯-酯)等具有生物降解性的聚合物。尤其对氧化环己烯(CHO)与CO₂(或酸酐)共聚,锌-钴双金属氰化络合物表现出了极高的催化活性和选择性。结合本研究组十多年的研究结果,本文讨论了双金属氰化络合物催化活性中心的可能结构和催化机理,提出了双金属氰化络合物催化聚合的共性难题和解决这些问题的方向。     

Fe-Al-α,α′-联吡啶催化体系催化马来酸酐与环氧丙烷开环共聚

马来酸酐与环氧丙烷开环共聚,所得聚酯具有功能团（C＝C）,可以通过接技、交联待方法改变其性能,马来酸杆与环氧化物开环共聚合成聚酯,所用催化剂通用有有机金属化合物和稀土 事物等,我们在铁系催化丁二聚合和马来酸酐与苯乙烯共聚的基础上,首次将Fe(acac)3-Al(i-Bu)3-α,α′－联吡啶催化剂用于马来酸酐与环氧化物开环共聚,发现该催化剂催化共聚反应具有时间短、收率高、共聚物交替度高等优点,并测定了共聚合反应动力学的参数。     

微波技术在生物可降解聚合物合成中的研究进展

阐述了微波合成技术及微波化学仪器的发展历史,综述了微波辐射技术在生物可降解聚合物合成中的特点和优势,并针对其在直接缩聚法、开环聚合法以及共聚合成可生物降解聚合物中的应用和研究成果做了重点介绍。研究发现微波辐射技术具有大大降低聚合反应的时间和能耗,提高反应聚合速率、收率,且具有一定选择性的特性。而作为一种新型高效的加热方式,微波辐射技术为生物可降解聚合物合成甚至更多高分子材料的合成提供了新的思路。     

开环可控聚合制备脂肪族聚酯的最新研究进展

近年来,作为生物降解高分子材料,脂肪族聚酯由于良好的生物降解性及生物相容性受到人们的广泛关注。脂肪族聚酯在环境友好材料和生物医用材料领域都具有极大的应用价值,目前,部分聚酯材料已经商品化。与此同时,脂肪族聚酯的合成方法尤其是活性开环聚合也成为学术界及工业领域的研究热点。采用开环聚合法得到的聚合产物化学组成精确、分子量分...     

新型PLA-PVP两亲性交联共聚物的初步研究

先以聚乙二醇(PEG)为中心嵌段,经消旋-丙交酯(D,L—LA)开环扩链,进而用丙烯酸酯封端制备了可生物降解交联剂。然后以辛酸亚锡为催化剂、甲基丙烯酸羟乙酯(HEMA)为共引发剂引发D,L—LA开环聚合,制备了末端双键功能化的大分子单体(PLA-HEMA)。最后以可降解交联剂、大分子单体和N-乙烯基吡咯烷酮(NVP)为原料,采用自由基聚合方法合成了新型可生物降解两亲性交联共聚物,并对其亲水性和力学性能进行了研究。     

有机小分子催化环醚与环状酸酐共聚研究进展

有机小分子催化聚合反应是合成化学领域新的研究方向。有机催化环醚(主要为环氧化物)与环状酸酐共聚制备聚酯的合成路线,由于单体具有来源广泛、有机催化剂低毒、对水和空气不敏感等特点,因而应用前景广阔。本文按有机小分子催化剂、环醚与环状酸酐的种类综述了近年来出现的有机催化共聚合成聚酯的反应,并详细讨论了该共聚反应及其机理,尤其是高催化活性和聚合可控性的Lewis酸碱对催化共聚的机理;提出了利用Lewis酸为增长链阴离子提供结构因素(如基团和电子结构效应)来调控聚合的方法。今后,催化环氧化物与环状酸酐共聚研究的中心任务仍然是发展新的高活性有机催化剂,并实现"活性"的全交替共聚反应,进一步提高共聚物的分子量,并实现共聚反应的化学选择性、区域和立体选择性的精确控制。     

聚酯酰胺的合成

聚（酯酰胺）（PEA）的主链中同时具有酯键和酰胺键,兼具了聚酯（polyester）的生物降解性和相容性以及聚酰胺（polyamide）优异的机械性能,在药物控释、组织工程以及热塑性弹性体等领域应用广泛。缩合聚合是合成聚酯酰胺最初的方法,近年来开环聚合（ROP）成为制备聚酯酰胺的主要策略,本文从环状单体均聚、环状单体共聚、环状单体和线形单体共聚等方面总结了聚酯酰胺合成的研究进展。同时,介绍了基于多组分聚合反应（MCP）的新合成方法,并对聚酯酰胺材料的发展进行了探讨和展望。     

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.