苯乙烯-双烯A交联共聚凝胶、溶胶的生成与转化

本文结合提取、凝胶色谱等方法测定了苯乙烯-双烯A交联共聚过程的转化率曲线。通过研究发现,凝胶在交联共聚一开始就产生,且整个反应过程都在不断地生成;转化率40％以前几乎无溶胶生成,此后生成的溶胶仍不断地向凝胶转化;刚生成溶胶时其分子量高、分布窄,其后分子量变低、分布变宽;T_g以上温度的热处理发生进一步聚合反应,当双烯A摩尔浓度<3.3×10~(-4)时,溶胶分数增加,A-MA摩尔浓度>5.0×10~(-4)时,凝胶分数增加,这是双烯A悬吊双键及单体苯乙烯进一步反应的结果。     

HEC/SiO2凝胶复合物包埋固定化葡萄糖氧化酶的研究

溶胶-凝胶技术;HEC/SiO2凝胶复合物包埋固定化葡萄糖氧化酶的研究     

流变学法研究交联聚合物凝胶的抗剪切性能

流变学法研究交联聚合物凝胶的抗剪切性能;交联聚合物;凝胶;屈服应力;流变学方法     

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征;N-异丙基丙烯酰胺;水凝胶;温敏性;快速响应     

可再生使用的溶胶-凝胶甲胎蛋白免疫传感器

可再生使用的溶胶-凝胶甲胎蛋白免疫传感器;溶胶-凝胶(sol-gel); 免疫传感器; 甲胎蛋白; 再生     

分子凝胶电解质的电导率研究

凝胶因子4,4'-二(硬脂酰胺基)二苯醚(BSDE)在水和非水介质(如二甲基甲酰胺、二甲基亚砜、碳酸丙烯酯等)中利用非共价键相互作用自组装成有序的三维纤维网络结构,使介质凝胶化.该凝胶被称之为分子凝胶.同样,BSDE也能使锂盐溶液凝胶化,制备一种新型分子凝胶电解质.水分子凝胶锂离子电解质的室温离子电导率达到10^-1～10^-2S·cm^-1,碳酸丙烯酯分子凝胶锂离子电解质的室温离子电导率也能达到10^-2～10^-3S·cm^-1.分子凝胶的离子电导率研究表明,锂盐在凝胶中的行为和其在溶液中的行为相似.在-35℃的低温下,分子凝胶的电导率与其溶液相比约低1～2个数量级.     

PMMA-TiO2纳米复合材料的制备

PMMA-TiO2纳米复合材料的制备;溶胶-凝胶法     

溶胶-凝胶固定葡萄糖氧化酶方法的改进

明胶;生物传感器;溶胶-凝胶固定葡萄糖氧化酶方法的改进     

P(NIPAAm-co-Aam)共聚凝胶和PAAc/P(NIPAAm-co-Aam) IPN凝胶的溶胀与释药性能

P(NIPAAm-co-Aam)共聚凝胶和PAAc/P(NIPAAm-co-Aam) IPN凝胶的溶胀与释药性能;N-异丙基丙烯酰胺;丙烯酰胺;丙烯酸;共聚;互穿聚合物网络;水凝胶;溶胀;释药     

离子键凝胶的现象及理论

本文研究并介绍了一类凝胶化现象—离子键凝胶;提出了该凝胶的形成原因及结构模型,并用多种方法进行了论证;推导了该凝胶的临界状态方程;阐述了其特点及在有关理论研究中的地位。     

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.