固体溶质在超临界三元系统中的溶解度

溶质在超临界流体中的溶解度数据是研究超临界流体技术的基础.本文对纯组分固体溶质有夹带剂存在的超临界流体三元系统中,夹带剂增大溶质溶解度的作用进行了总结,述评了夹带剂增大溶质溶解度的机理和常用的计算模型.此外,针对两种固体混合溶质共存于超临界流体中的三元系统,讨论了混合溶质共存对彼此溶解度的影响及其相关的理论假说和计算模型.     

微流体驱动与控制技术*

在微流控系统所需的功能单元中,微流体驱动与控制操作单元尤为重要。微系统条件下,表面张力的影响变得十分明显,在工程意义上,常规的流体体积流动的驱动方法在微管道中往往效果不好甚至是不可行的。本文简要评述了用于微流体驱动的机械微型泵技术,基于电、光、磁等的非机械微型泵技术,以及微流体的高效混合控制等技术的研究现状,对微流体驱动与控制的未来作了展望。     

具有最高共溶温度高分子共混体系的压力诱导相容性热力学研究

根据具有最高共溶温度高分子共混体系的压力诱导相容实验结果, 结合Sanchez-Lacombe格子流体理论和文中给出的关于嵌段共聚物标度参数组合规则, 对高分子体系在压力作用下的混合焓、混合组合熵、混合空位熵和Gibbs混合自由能等热力学性质进行了研究. 研究结果表明Sanchez-Lacombe格子流体理论和新的关于嵌段共聚物标度参数组合规则可以用来描述压力作用下的具有最高共溶温度高分子共混体系的压力诱导相容性.     

超临界CO_2萃取中草药活性成分溶剂特性研究

针对超临界二氧化碳流体的局限性和中草药中活性成分的特殊性,研究了超临界二氧二化碳流体、改性剂和混合溶液的溶解度参数,提出了改性剂的选择原则。结果表明:萃取温度和压力是影响超临界二氧化碳流体和混合溶剂溶解度参数的主要因素,改性剂的种类和浓度影响萃取体系的溶解特性。     

微流控技术在纳米合成中的应用

微流控技术具有微型化、集成化的特点,且所合成产物形貌和单分散性好,已经越来越多的被应用于纳米材料的合成中。 本文对微流体技术在纳米材料合成中的应用做了系统的阐述。 对微流控芯片中流体流动、混合机理进行了介绍,并详细介绍了微流控芯片的制作工艺,展望了微流体技术在合成纳米材料中应用前景。     

不锈钢侧顶复吹AOD精炼过程中熔池内流体混合特性初探

利用水力学模拟,对不锈钢侧顶复吹AOD精炼过程中熔池内流体混合特性作了初步研究.模型和原型(包括喷枪)间的几何相似比为1/4.基于喷枪内气流特性参数的理论计算较合理地确定了模型吹气量,考察了侧枪数及枪位和侧、项吹气量对混合特性的影响.结果表明,吹炼过程中流体循环运动活跃,熔池中不存在明显的"死区",混合效果良好.侧吹主枪气体流量对熔池内流体的混合影响最大,侧吹副枪气流可使混合效率提高,而顶枪气流使混合时间延长.对应于工艺规定的顶吹氧量,对于侧枪,6枪、27°夹角,5枪、22.5°或27°夹角都能达到大体相当的良好的混合效果.得到了混合时间与主、副侧枪及顶枪气量、两相邻侧枪间夹角和侧枪数的关系.     

硅酸盐岩石微孔中流体混合物扩散系数的分子动力学模拟

用计算机模拟研究了受限于硅酸盐岩石微孔中等摩尔氩氪流体混合物的扩散系数.为验证程序的正确性,分别将宏量条件下氩和氪的分子动力学模拟值与文献实验值进行了比较.然后,对受限于硅酸岩平板壁面中氩氪流体混合物的扩散系数进行了模拟计算.根据计算结果提出了五个不同对比壁间距下氩氪混合流体扩散系数的经验模型,这些模型可应用于工业估算.     

漆酚基乳化剂对水包油型生漆乳液流变行为的影响

以漆酚基乳化剂(UE)和聚乙烯醇(PVA)为混合乳化剂制备了水包油(O/W)型生漆乳液(RLE),用RHEOMETER(R/S)对RLE的流变性进行了研究.讨论了UE10浓度(cUE10)、混合乳化剂浓度(cME)、UE的结构对RLE流变性的影响.结果表明,RLE的黏度随着cUE10的增加而增大,用不同cUE10制备的RLE都有剪切变稀的特性,表现出假塑性流体的行为;当cME≤6.7%,RLE表现出假塑性流体的行为,而当cME≥10.0%,RLE则表现出膨胀型流体的特征;用不同UE制备的RLE均表现出假塑性流体的特征,其流变行为符合Herschel-Bulkley模型,随着UE分子中聚氧乙烯链的增长,RLE的黏度增大,RLE粒子间所形成的某种静态空间网状结构强度增强.     

集成试样引入微泵的微流控芯片毛细管电泳分析系统

微流控分析是20世纪90年代以来迅速发展的一门前沿学科,它的出现使化学检测设备的微型化、集成化与便携化成为可能.微流控分析系统的核心是微流体操纵和控制,而微流体的驱动则是实现微流控操作的基础.     

低温非水环境中疏水缔合聚丙烯酸钠与两性离子表面活性剂的相互作用

疏水缔合聚合物和表面活性剂是构建黏弹性流体的重要物质, 二者的相互作用对流体性质具有显著影响, 一直是该领域的研究热点, 但此前的研究仅聚焦于水溶液中室温及以上温度范围, 而零下极端低温环境中的相互作用尚未涉及. 本文以疏水缔合聚丙烯酸钠(HMPA)为模型聚合物, 研究了低温(-20~20 ℃)环境中其与两性离子表面活性剂N-(顺-二十二碳-13-烯酸酰胺基丙基)-N,N-二甲基羧酸甜菜碱(EDAB)在乙二醇/水混合溶剂中的相互作用及混合体系的流变性质. 先后考察了HMPA溶解于纯水和乙二醇/水混合溶剂时的流变行为和HMPA-EDAB在乙二醇/水混合溶剂中的流变行为及自组装结构形貌. 研究发现, 加入50%(体积分数)的乙二醇会阻碍HMPA疏水支链形成缔合结构, 减弱其增黏性能, 但同时也会大幅降低体系的冰点. 在HMPA- EDAB混合体系中, HMPA疏水支链会进入EDAB胶束内核自组装形成混合胶束. 混合胶束的形貌取决于 HMPA和EDAB的浓度及环境温度, 进而影响体系的流变行为. 零下的低温有助于EDAB形成蠕虫状胶束, 因此HMPA与EDAB表现出更强的协同增效作用.     

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.     

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.     

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.     

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.     

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.     

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.