含磺酸酯基液晶的合成

把硫原子引入液晶分子,取代液晶分子中的碳原子和氧原子可得到含硫代苯甲酸酯［１］、砜基［２］、亚砜基［３］和亚磺酸基［４］等结构的液晶化合物,性能独特．但含磺酸酯基的液晶化合物尚未见文献报道．本文应用Ｎ,Ｎ二环己基碳二亚胺（ＤＣＣ）和４Ｎ,Ｎ二甲...     

几种新液晶作固定液分离二元取代苯异构体

Kelker和Dewar等人曾把液晶用作气相色谱固定液分离二元取代苯异构体取得很好的效果,此后很多研究者把近两百种液晶亦都用于气相色谱固定液。在研究和使用的液晶固定液中,芳羧酸酯类液晶被认为具有较好的热稳定性和分离选择性,国内研究较多的也是这一类液晶,而且已有商品。为了进一步研究这类液晶以扩大品种,我们在对苯二酚酯液晶的苯环上引入不同类型和数量的极性基团,并在玻璃毛细柱上考查其对二元取代苯异构体的分离性能。     

新型含磺酸基Schiff碱型液晶化合物的合成与表征

对羟基苯甲醛与对氨基苯磺酸经缩合反应制得Schiff碱化合物(1).对羟基苯甲酸经醚化、酯化、酰氯化后再与1完成酯化反应合成了新型含磺酸基Schiff碱型液晶化合物--[4-(对磺酸苯亚胺基)甲苯基]-4-(ω-甲基丙烯酸乙氧基酯)-苯甲酸酯(5),其结构经1H NMR和IR表征.偏光显微镜与DSC检测结果表明,5具有近晶A型液晶特性,液晶变化范围189.45 ℃～267.65 ℃.     

聚对偶氮氧苯酚酯系列热致性液晶高分子的相转变

合成含有不同亚甲基数（ｎ＝４—１２，１４）的主链型热致性液晶高分子──聚对偶氮氧苯酚二元羧酸酯．用ＤＳＣ和ＦＴＩＲ观测了相转变的奇偶效应，揭示了液晶相转变过程中分子间相互作用力性质的变化．并与聚２，２＇－二甲基对偶氮氧苯酚二元羧酸酯系列进行了比较，讨论了中介单元的对称性对液晶高聚物相转变和对液晶相稳定性的影响．     

侧链胆甾液晶聚合物及弹性体的液晶性能研究

把胆甾液晶单体 4 烯丙氧基苯甲酸胆甾醇酯 (Mch)分别和向列液晶单体 4 烯丙氧基苯甲酰氧基 4′ 甲氧基苯 (Mn) ,向列液晶交联剂 2 叔丁基对苯二酚双 [4 (6 丙烯酰氧基己氧基 )苯甲酸酯 ](Mnc)接枝到聚硅氧烷链上 ,得到系列侧链液晶聚合物Pn 系列和液晶弹性体Pe 系列 .通过热分析、偏光显微分析和X 射线分析等手段分别研究了向列液晶单体和向列液晶交联剂对含同一胆甾液晶基元聚合物的影响 .结果表明 ,向列液晶单体的摩尔百分比在 80 %以下 ,液晶聚合物Pn 系列为胆甾型液晶 ,在研究的范围内 ,液晶弹性体Pe 系列也为胆甾型液晶 ,Pn 系列和Pe 系列都具有较宽的液晶相范围 ,热分解温度均在 2 80℃以上 .     

含偶氮基团的聚丙烯酸酯型功能侧链液晶高分子的性能及其应用前景

综述了基于具光致双折射和光存储性质的偶氮功能基团的新型功能性侧链液晶聚丙烯酸酯的液晶性质、光电性质及应用前景.指出该类聚合物是一类非常重要的非线性光学材料 ,一般显示热致性向列型或近晶型液晶相, 液晶相转变温度和液晶态温度范围随链结构的不同发生显著变化,具有较短的电场及光场响应时间.此类材料在不断开发研究下可望用作长久的高对比度的光学信息储存材料.     

聚甲基丙烯酸胆甾醇酯共聚物的合成、结构与性能研究 Ⅳ.PMACE的相态转变及光学性质

Finkelmann和等人对侧链胆甾型高分子液晶的研究表明,将具有液晶功能的低分子基团,经过一个软段连接到柔性高分子主链上的梳型高分子在一定的温度下可以形成液晶态,调节侧链高分子液晶的分子结构、软段长度,可以改变其相态转变温度及微区形态。前已报导具有不同侧链结构的聚甲基丙烯酸胆甾醇酯共聚物的合成、相态转变及光学性质,本文通过对聚甲基丙烯酸胆甾醇乙烯酯共聚物(PMACE)的液晶态及结晶态的微细结构及相态转变与胆甾侧链含量关系的研究,给出了液晶态的形成条件及结构特征。     

聚甲基丙烯酸羟乙胆甾接枝共聚物(PHCEM)的合成、结构与性能研究 Ⅱ PHCEM的相态转变

本文通过偏光显微镜、DSC、X射线衍射及选择散射等手段,深入研究了甲基丙烯酸羟乙酯胆甾醇甲苯二异氰酸酯接枝共聚物的相态转变。在一定的条件下,侧链上的胆甾基团可自由取向,形成胆甾相液晶。     

含有联苯和肉桂酸酯基团的侧链液晶共聚物的合成与表征

合成了两种含有联苯刚性基元的甲基丙烯酸酯单体M1和M2,其中M1为含有可光交联的肉桂酸酯端基的单体.通过溶液自由基聚合,得到一系列含不同比例M1和M2单体单元的聚丙烯酸酯类侧链液晶共聚物.采用1H-NMR、FT-IR等方法对单体和聚合物的结构进行了详细表征.用示差扫描量热法、偏光显微镜以及广角和小角X-射线衍射对单体和聚合物的液晶性进行了研究.结果表明,末端为肉桂酸酯基团的单体M1无液晶性,其均聚物P1有微弱的液晶性,而端基为正丁基的单体M2及其均聚物P9则表现出近晶相液晶行为.共聚物P2~P5均为向列型液晶,P6~P9则为近晶型液晶.随在聚合物中M2单体含量的增加,共聚物的玻璃化转变温度、熔点及清亮点温度均呈现增加趋势.     

棒状双酯基磁性液晶的合成及其磁性和液晶性

以端基为C3及C5取代的多环酸为原料, 合成了6个具有双酯基中介核, 末端为TEMPO (TEMPO＝2,2,6,6-tetramethylpiperidine-1-oxyl)的磁性分子. 用元素分析, 红外光谱, 质谱等对其结构进行了表征; 利用超导量子干涉仪(SQUID磁学测量系统), 顺磁共振仪, 差热扫描量热仪以及热台偏光显微镜等对化合物的磁性质和液晶性质进行了测定, 提出了该类化合物同时具有磁性及液晶性所应具备的分子结构; 最后, 将磁性液晶与液晶材料进行了混配, 测试了混配液晶的光电性能. 结果表明, 6个化合物均同时具有磁性和液晶性, 其液晶相温度区间在16～24.8 ℃, 呈典型的向列相织构; 磁性液晶与液晶材料混配后可明显改善液晶材料的响应灵敏度.     

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.