含硝基偶氮苯侧基的丙烯酸酯液晶聚合物的合成、结构与性质研究(Ⅲ)——分子结构对结晶的影响

以含硝基偶氮苯侧基的丙烯酸酯液晶聚合物为研究对象,利用DSC、WAXD、偏光显微镜等手段研究了分子结构对侧链液晶聚合物结晶行为的影响.结果表明:丙烯酸酯类液晶聚合物的晶区是由介晶基团的规整排列形成的,大分子主链和柔性间隔基不参与结晶.随着柔性间隔基长度的增加,晶区分子排列有序性提高,结晶度增大;非晶共聚组分MA含量的增加,限制了介晶基团的有序排列,当MA含量超过83％后,只得到非晶共聚物.     

含硝基偶氮苯侧基的丙烯酸酯液晶聚合物的合成,结构与性…

以含硝基偶氮苯侧基的丙烯酸酯液晶聚合物为研究对象，利用ＤＳＣ、ＷＡＸＤ、偏光显微镜等手段研究了分子结构对侧链液晶聚合物结晶行为的影响。结果表明：丙烯酸酯类液晶聚合物的晶区是由介晶基团的规整排列形成的，大分子主链和柔性间隔基不参与结晶。随着柔性间隔基长度的增加，晶区分子排列有序性提高，结果度增大；非晶共聚组分ＭＡ含量的增加，限制了介晶基团的有序排列，当ＭＡ含量超过８３％后，只得到非晶共聚物。     

一种侧链液晶高分子的合成与表征

合成了一种主链为甲基丙烯酸酯 ,侧链是三个苯环以酯键相连的介晶基元 ,柔性间隔段为两个亚甲基的新的侧链液晶高分子 .聚合物和单体的化学结构、液晶相转变和液晶态织构采用红外光谱、核磁共振、偏光显微镜、差热分析和广角X光衍射进行了表征 .研究表明 ,单体呈现近晶相和向列相两个液晶相 ,聚合物在很宽的温度范围内呈向列相 .该单体和聚合物在一定条件下可形成固化诱导条带织构     

含联苯结构侧链液晶聚合物的合成及相行为的研究

液晶聚合物从结构上可分为3种:侧链型、主链型和主侧链型。侧链型液晶聚合物主要是聚丙烯酸酯类、聚硅氧烷类以及磷腈聚合物类。Gray等对聚丙烯酸酯类含不同取代基的联苯结构液晶聚合物进行了研究,结果表明无间隔基且取代基为氰基和饱和脂肪基时,该聚合物呈现近晶型液晶行为。为了增加介晶单元的长径比及刚性,本文在聚甲基丙烯酸酯侧链     

手性丙烯酸酯侧链液晶共聚物的研究

手性丙烯酸酯侧链液晶共聚物的研究何流，张树范，漆宗能，王佛松（中国科学院化学研究所北京１０００８０）关键词手性液晶，近晶相，丙烯酸酯共聚物侧链液晶聚合物既具有小分子液晶的光电敏感性，又具有高分子聚集态结构性质，在光学记录、贮存和显示材料领域有潜在的实...     

在电场和磁场下手性侧链丙烯酸酯液晶聚合物的行为

在电场和磁场下手性侧链丙烯酸酯液晶聚合物的行为江雪平金顺子漆宗能张树范（中国科学院化学研究所北京１０００８０）关键词手性侧链丙烯酸酯液晶聚合物，红外二向色性，液晶分子排列含有手性液晶基团的聚合物，分子中含有不对称碳原子，在一定条件下使液晶聚合物...     

一类新的刚性链侧链型液晶高分子的合成

以自由基聚合方法，合成了一系列含有三个苯环通过酯键相联的液晶性单体及其聚合物．在这类新的液晶高分子中，刚性液晶基元不通过柔性间隔基而直接竖挂在聚甲基丙烯酸酯大分子主链上．这些高分子有很高的玻璃化转变温度，表明其分子链刚性较大，因而代表了一类新的刚性链侧链型液晶高分子．它们的液晶行为用ＤＳＣ、偏光显微镜和Ｘ－光衍射进行了表征．发现所有单体和聚合物均为向列型热致性液晶．     

用环氧乙烷低聚物为柔性间隔的手性侧链液晶高分子的合成

本文用乙氧基做为主链与侧链的柔性间隔，合成了手性侧链液晶高分子．通过ＤＳＣ，热台偏光显微镜及Ｘ－衍射等手段，研究了柔性间隔链长对液晶行为的影响．结果表明，这类液晶高分子有较宽的相变温度范围．聚合物的相变温度及液晶态的形成与柔性间隔链长有关．     

刚性链侧链型液晶高分子合成与研究

以自由基聚合方法，合成了一系列含有３个苯环通过酯键相联的液晶性单体及其聚合物，这类刚性液晶基元不通过柔性间隔基而直接竖挂在聚丙烯酸酯大分子主链上，具有很高的Ｔｇ·ＤＳＣ及偏光显微镜结果表明，所有的单体和聚合物均为向列型热致性液晶。     

含1,3,4-噁二唑甲壳型液晶聚合物的合成与表征

甲壳型液晶聚合物（mesogen-jacketed liquid crystal polymer,MJLCP）是1987年由周其凤教授[1]首先提出的概念.从化学结构看,甲壳型液晶聚合物属于侧链型,由烯类单体经链式聚合制得,容易得到高分子量的产物,具有一般柔性侧链型液晶聚合物的一些优点.但是与柔性侧链型液晶聚合物不同的是,MJLCP分子中的刚性液晶基元是通过腰部或重心位置与主链相联结的,在主链与刚性液晶基元的侧基之间只有很短或者没有柔性间隔基.由于在这类液晶聚合物的分子主链周围空间内刚性液晶基元的密度很高,分子主链被由液晶基元形成的外壳所包裹并被迫采取相对伸直的刚性链构象.因此,这类液晶聚合物又和主链型刚性链液晶聚合物相似,具有较明显的链刚性.近年来,周其凤课题组围绕甲壳型液晶聚合物深入开展了分子设计与合成、分子结构与性能等多方面的研究.其中,设计合成具有特定功能的甲壳型液晶聚合物是在以往研究工作和学科交叉融合的基础上发展起来的一项新的研究工作.将一些有特殊功能的基团引入到甲壳型液晶聚合物中会使其具有崭新的特性.     

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.     

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.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).