含柔性间隔基的热致液晶性共聚酯的合成

 将己二酸、辛二酸、癸二酸、1,10-十二烷基羧酸经酰氯化后,分别与对羟基苯甲酸合成,得到了四种二元羧酸以及与其相应的四种二元酰氯,并发现前者具有热致液晶性。 将上述单体与对苯二酚、氯代对苯二酚以及联苯二酚用溶液缩聚的方法合成了十二种规则共聚酯,并用热台偏光显微镜、DSC、X-衍射等方法对共聚酯进行了表征。结果发现各共聚酯均为向列型热致液晶,并都具有较宽的液晶态温度范围。通过改变分子结构可使共聚酯的熔点在150—300℃之间变化。     

一类可纺丝的全芳香热致性液晶共聚酯的合成和表征

利用Higashi芳香聚酯直接缩聚法的原理 ,采用一步混合投料直接缩聚的方法 ,以对羟基苯甲酸(PHB)、间苯二甲酸 (MPA)、4 ,4′ 二羟基二苯酮 (DHBP)和对苯二酚 (HQ)为单体原料 ,合成了全芳香共聚酯 .该合成方法反应条件温和 ,简单易控 ,产物分子量高 .用差热分析 (DSC)、热重分析 (TA)、偏光显微镜 (PLM)、广角X 射线衍射 (WAXD)等测试分析手段对共聚酯的热性能和液晶特性进行了表征 .研究结果表明 ,利用此方法合成所得的聚合物呈明显的向列型热致液晶特性 ,热稳定性高 ,并具有极易成纤的特点 ,有望成为一种可用于纺丝的全芳香热致液晶共聚酯材料     

热致液晶性聚合物——含萘环主成分为对羟基苯甲酸的全芳香族共聚酯

由对乙酰氧基苯甲酸、对苯二酚二乙酯、2,6-萘二甲酸及间苯二甲酸四种单体通过熔融缩聚反应,合成了全芳香族四组分共聚酯。在一定的组成范围内,共聚酯熔体有很好的液晶性。本文重点讨论了聚合物的组成与性质的关系,热谱特征和液晶相行为。     

热致液晶性聚合物——含单取代苯环和扭曲成分的全芳香族共聚酯

本文报道了由氯代对苯二酚/甲基代对苯二酚和对苯二甲酸以及二种能导致分子链扭曲和弯折的成分——4,4′-二羟基二苯醚和间苯二甲等合成的全芳香族共聚酯。一定组成范围的四元共聚酯具有低熔点,宽液晶相区,易成纤的特点。重点讨论了分子组成-转变行为-液晶性和成纤性的关系,并对液晶相的形态结构进行了表征。     

1,8-辛二酸改性热致液晶共聚酯的制备及其性能

以对羟基苯甲酸、对苯二甲酸和对苯二酚为共聚单体，经乙酰化和熔融缩聚两步法合成三元热致液晶共聚酯。引入长链脂肪族化合物1,8-辛二酸作为改性单体，按不同比例代替对苯二甲酸，制备了一系列含柔性链段的新型四元热致液晶共聚酯。通过傅里叶红外光谱(FT-IR)和核磁共振碳谱(¹³C-NMR)对共聚酯结构进行表征，采用差示扫描量热(DSC)和热失重分析(TGA)表征其热性能，采用偏光显微镜(POM)和X射线衍射(XRD)分析其液晶性能。研究表明，三元液晶共聚酯熔点达407℃，热稳定性优异。随着1,8-辛二酸含量增加，四元共聚酯熔点显著降至214℃，热稳定性较好，最大热分解温度达到428℃。该系列共聚酯显示了典型的向列型液晶织态结构。1,8-辛二酸的引入显著改善了液晶共聚酯的可加工性。     

含4，4＇－二羟基二苯酮热致液晶四元共聚酯的合成与表征

含４，４＇－二羟基二苯酮热致液晶四元共聚酯的合成与表征董德文，韩平，倪玉山，丁孟贤，韩伟（中国科学院长春应用化学研究所长春１３００２２）（吉林化工学院化工系吉林）关键词　热致液晶，共聚酯，向列型，二羟基二苯酮关于热致液晶芳香族聚酯的研究已有大量的报道...     

含T-型和棒型两种液晶基元的主链型液晶共聚酯的合成和表征

以４，４′（α，ω 癸二酰氧）二苯甲酰氯，２ （４′ 乙氧基苯基）对苯二酚和联苯酚为单体，通过溶液缩聚反应，合成了一系列含Ｔ 型和棒型两种液晶基元的主链型芳族共聚酯．采用ＤＳＣ、偏光显微镜和Ｘ 射线衍射方法研究了共聚物的液晶行为，发现所有聚合物均有很好的热致液晶性且随聚合物中联苯酚用量的改变，共聚物的熔点（Ｔｍ）和液晶态清亮点（Ｔｉ）呈规律性变化．     

对苯二甲酰类全芳族聚酯结构与性能的研究

本文以对苯二甲酰氯分别和五种二元酚单体,对苯二酚(HQ)、邻氯对苯二酚(CHQ)、联苯二酚(BP)、双酚A(BPA)、4,4′-二羟基二苯基甲烷(BPM)进行溶液缩聚,制备了一系列全芳族均聚酯和共聚酯,作了各种性能表征。考虑了单苯二酚和双苯二酚单体对聚合物的熔融温度、热分解温度、相变热效应、溶解性、液晶态及织态结构、液晶相范围和光学行为等影响,并讨论了二酚单体作为致介单元的分子结构条件,得到HQ、CHQ和BP为致介单体,BPA和BPA为非致介单体的结论。     

4,4’-对苯二甲酰基二氧二苯甲酸与脂二醇的共聚及液晶性能研究

以对苯二甲酸和对羟基苯甲酸为起始原料合成了液晶单体4，4’-对苯二甲酰二氧二苯甲酰氯（TOBC），用TOBC分别与癸二醇-1，10，己二醇-1，6，戊二醇-1，5，丁二醇-1，4和乙二醇进行缩聚反应，生成了一系列主链型热致液晶共聚酯。用DSC、热台偏光显微镜和X-射线衍射仪等对合成的共聚酯的液晶行为进行了表征，结果表明，合成的共聚酯均为向列型热致液晶，其液晶温度范围在20℃－68℃之间，并随着脂肪族二醇中亚甲基（CH2）单元的增加，共聚酯的熔融转变温度（Tm）和各向同性温度（Ti）均有规律的变化。表明主链型液晶共聚酯分子中柔性间隔基的大小对共聚酯的液晶性质有着明显的影响。     

4,4‘—对苯二甲酰基二氧二苯甲酸与酸二醇的共聚及液晶性能研究

以对苯二甲酸和对羟基苯甲酸为起始原料合成了液晶单体４,４’－对苯二甲酰地氧二苯甲酰氯（ＴＯＢＣ）,用ＴＯＢＣ分别与癸二醇－１,１０,己二醇－１,６,戊二醇－１,５,丁二醇－１,４和乙二醇进行缩聚反应,生成了一系列主链型热致液晶共聚酯。用ＤＳＣ、热台偏光显微镜和Ｘ－射线衍射仪等对合成的共聚酯的液晶行为进行了表征。结果表明,合成的共聚互均为向列型热致液晶,共液晶温度范围在２０℃￣６８℃之间,并随着脂肪     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.