甲壳素类液晶高分子的研究 Ⅰ侧基长度对羧酰化甲壳素的液晶性的影响

四种羧酰化甲壳素即乙酰化、丙酰化、丁酰化和己酰化甲壳素在二氯乙酸溶液中均呈现胆甾型溶致液晶相．临界浓度随侧基长度增加而略有增加,衍生物的临界浓度明显都比原甲壳素高许多,这些规律都可以用链刚性的变化来解释．四种羧酰化甲壳素在剪切时均能形成条带织构,而且能形成条带织构的最低浓度有明显差别,随侧基长度增加而提高,进一步表明侧基较长,液晶性减少．     

分子量对壳聚糖溶致液晶性的影响

三种不同分子量的壳聚糖[脱乙酰度均为(84±1)%]在二氯乙酸溶液中都呈现胆甾型溶致液晶相.临界浓度随分子量增加而降低,但均比同样聚合度的甲壳素的高.用偏光显微镜法和激光小角散射法测得的胆甾液晶相的螺距很相近,在浓度相同时,其值随分子量的增加而减小.     

聚电解质──壳聚糖浓溶液流变学性质研究：浓度、温度、溶剂pH值和外加盐对粘度及流动性的影响

本工作用日本岩本ＲＰＸ－７０５多功能流变仪测定了在不同浓度，温度，溶剂ｐＨ值和外加盐浓度对壳聚糖在甲酸水溶液中其浓溶液粘度η随剪切速率γ的变化关系，讨论了浓度，温度等对溶液粘度，流动活化能Ｅγ和流动指数ｎ的影响。发现溶剂ｐＨ值减小或溶液中外加盐浓度增加，溶液粘度变小，ｎ增大，表明非牛顿流动性减弱，并且进一步了零剪切粘度ηｏ和外加盐浓度Ｃｓ的依赖关系。     

孪尾疏水缔合三元共聚物的粘度行为:水解度的影响

以十二烷基硫酸钠(SDS)为表面活性剂,利用氧化还原体系、采用前加碱共聚-共水解的方法制备了孪尾疏水缔合水溶性三元共聚物聚(丙烯酰胺／丙烯酸钠／N,N-二己基丙烯酰胺)[P(AM/NaAA／DiC6AM)],研究了P(AM／NaAA／DiC6AM)稀溶液及亚浓溶液的性能。随理论水解度的增加,P(AM／NaAA／DiC6AM)水溶液的特性粘数[η]增加,Huggins常数KH减小。P(AM／NaAA／DiC6AM)水溶液的表现粘度随理论水解度的增加而增加,随温度、剪切速率的增加而降低,随剪切速率的增加开始时降低较快而后变化较小。P(AM／NaAA/DiC6AM)在盐溶液中随NaCl、CaCl2质量浓度的增加,出现盐增粘现象;理论水解度不同的P(AM／NaAA／DiC6AM)与SDS水溶液的表现粘度在wSDS=0．050～0．400g／L范围内随SDS质量浓度的变化差别不大。     

聚电解质──壳聚糖浓溶液流变学性质研究：浓度、温度、溶剂pH值和外加盐对粘度及流动性的影响

本工作用日本岩本ＲＰＸ－７０５多功能流变仪测定了在不同浓度、温度、溶剂ｐＨ值和外加盐浓度对壳聚糖在甲酸水溶液中其浓溶液粘度η随剪切速率γ的变化关系．讨论了浓度、温度等对溶液粘度、流动活化能Ｅ_γ和流动指数ｎ的影响．发现溶剂ｐＨ值减小或溶液中外加盐浓度增加，溶液粘度变小，ｎ增大，表明非牛顿流动性减弱，并且进一步讨论了零剪切粘度η_０和外加盐浓度Ｃ_ｓ的依赖关系．     

壳聚糖在1-乙基-3-甲基咪唑醋酸盐溶液中的流变行为

离子液体1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）对壳聚糖具有良好的溶解能力。利用新一代旋转流变仪哈克MARS-Ⅲ考察了壳聚糖-[EMIM]Ac溶液的稳态流变和动态流变性能。稳态流变结果表明：当低黏均分子量壳聚糖离子液体溶液的质量分数在3%以下时,溶液呈牛顿性流体特征,高于此质量分数时溶液呈假塑性流体特征;壳聚糖离子液体溶液的黏度、结构黏度指数随着温度升高而降低;在同一质量分数下,溶液黏度随壳聚糖黏均分子量的增大而增加,溶液的恒剪切活化能黏流活化能随着剪切速率的增大而降低。动态流变结果表明：溶液的储能模量和损耗模量随着温度的升高而下降,储能模量与损耗模量存在一个交叉点,该交叉点随着温度升高向高频区移动。     

羧甲基羟丙基瓜尔胶的流变特性

考查了羧甲基羟丙基瓜尔胶溶液的流变特性,发现其水溶液呈典型的假塑性,不同浓度下溶液表观粘度随剪切速率的变化可以用Ostwald-Dewaele方程描述;零切粘度与温度的关系符合Andrade方程;溶液的粘度在酸性条件下随溶液pH的减小迅速降低,在碱性条件下则变化不大;溶液对NaCl很敏感,表现出典型的聚电解质的特征。     

低剪切速率下聚乙二醇／KCl／蒙脱土分散体系的剪切稠化现象

用Hakke RS75流变仪研究了聚乙二醇（PEG）／KCl/蒙脱土分散体系的流变性 。结果发现，当KCl和聚乙二醇浓度在一定范围内时，体系随剪切速率增加，表现 出剪切稀释－剪切稠化－剪切稀释的复杂结构变化，并且剪切稠化发生在低剪切速 率区。KCl浓度继续增加，剪切稠化逐渐减弱。TME表明，蒙脱土分散体系中加入 KCl使得蒙脱土颗粒聚集，而聚乙二醇导致经微絮凝；二者同时加入，体系形成细 枝条状的空间稳定结构。     

联接基长度对Gemini表面活性剂流变性质的影响

用毛细管振荡剪切流动法研究了联接基团为聚亚甲基链的阳离子Gemini表面活性剂的流变性质。实验结果表明,无论是普通单链单头基或Gemini表面活性剂,其流变性质主要由胶团的大小和形状所决定;随着联接基团长度的增加,胶团的轴比率变小,导致流动阻力减小,粘度降低。此外对于球形和棒状胶团溶液,其流变性质主要以粘性为主．弹性可忽略不计。在低剪切速率下,溶液属于牛顿型流体;而在高剪切速率下,则表现出准塑性流体性质。     

褐煤中水分对油煤浆流变性质的影响

针对云南褐煤,用真空干燥脱水和恒温恒湿箱处理获得了不同含水率的褐煤,在常温常压(t=19.3℃,p=1.01×105Pa)条件下研究了褐煤含水率对油煤浆流变特性的影响。研究表明,原料煤含水率对油煤浆黏度和流变特性有一定的影响。随褐煤含水率增加,油煤浆黏度先减小后增加。油煤浆浓度不同,剪切速率不同,黏度出现最低值的含水率值wmin也不同。浓度为45.45%的油煤浆,剪切速率小于4.4 s-1时,wmin为9.20%;剪切速率大于4.4 s-1时,wmin为7.80%。浓度为55.56%的油煤浆,剪切速率小于1.32 s-1时,wmin为7.40%;剪切速率大于1.32 s-1时,wmin为10.00%。随剪切速率变化,油煤浆黏度上下行曲线之间形成滞后环,表明油煤浆体系有触变性,并且不同含水率煤浆体系触变性不同,含水率越大,触变性越明显。实验中不同含水率褐煤油煤浆都属于假塑性流体,且含水率对模型参数有一定的影响。     

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.