Der Einfluß von Grenzflächenerscheinungen auf den Stoffübergang und die Prozeßführung in Gegenstromkolonnen mit überkritischem CO2

Zusammenfassung Mittels des Einsatzes einer Hochdrucksichtzelle wurden Eigenschaften der Kontaktbereiche in Trennverfahren mit unterschiedlichen wäßrigen Lösungen und CO₂ unter hohen Drücken untersucht. Die Methode des hängenden Tropfens wurde zur Messung der Grenzflächenspannung bis zu Drücken von 280 bar angewandt. Der mit dem Druck abnehmende Verlauf weist nach der Gibbs'schen Theorie auf die Anreicherung von CO₂ in der Phasengrenze. Weiterhin wurde die für Packungskolonnen bedeutsame Feststoffbenetzung in Abhängigkeit von Druck und Oberflächenbeschaffenheit des Feststoffes untersucht. Der die Feststoffbenetzung charakterisierende Kontaktwinkel wurde mittels der Methode der gekippten Platte vermessen und ergab eine schlechtere Benetzung bei höheren Drücken und glatten Stahloberflächen.

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The effect of interfacial phenomena on mass transport and performance of separations in countercurrent columns with supercritical CO₂

Interfacial phenomena affecting countercurrent separation processes have been studied in systems containing aqueous solutions and CO₂ at elevated pressures by means of a high pressure optical cell. The pendant drop method was applied in order to measure the interfacial tension up to 280 bar. The decreasing course as a function of the pressure is due to the adsorption of CO₂ at the interface according to Gibbs' law. Further, wetting characteristics have been investigated as they are of considerable importance to packed columns. Therefore, the contact angle was determined by the method of the tilting plate and came out to increase with pressure and smoothness of the solid surface, indicating the loss of wettability.

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广义风险过程中渐近方差的非参数估计

本文对广义风险过程中的渐近方差作了非参数估计,得出并证明了两个定理,为广义风险过程中破产概率的区间估计作了理论准备．     

3,3,6,6-四甲基-9-邻氯苯基-1,8-二氧代-3,4,5,6,7,9-六氧化氧杂蒽的合成和晶体结构

标题化合物C23H25对O3Cl是由邻氯苯甲醛与5，5-二甲基1，3-环己二酮在N，N-二甲基甲酸腹中反应而得。结构通过单晶X-射线衍射法确定，其晶体属于单科晶系，空间群=1632。晶体结构用直接法解出，使用全矩阵最小二乘法对原子参数进行修正，最后的偏离因子为R=0．054，Rw一0．063。在晶体结构中，吡喃环与苯环之间的两面角为92．43°。     

Total Synthesis of Several 8, 8",-Biflavones

8,8"-Biflavonoidsareantw0rtantclass0fbiflavonoids.Asasystematicresearchofthe8,8"-biflav0noids,wehavepreviouslyreportedthestudyonthereactionof2'-hydroxychaloneswithl2-H2SO4-DMSOsystem.'InthispaPer,thesynthesisof5,5",7,7',-tetTameth0xy-8,8"-biflavonela2,4,4",7,7"-tetramethoxy-8,8"-biflavone1b',4',4",,5,5,',7,7"-hexamethoxy-8,8"-biflav0ne1c4and4,4"-dibenZyl0xy-5,5",7,7"-tetramothoxy-8,8"-biflavoneldisreported.ThesyntheticmethodisshownintheSchemebelow.2-Hydroxyacet0phenonescondensedwithsubsti…     

Synthesis of some 4-substituted-2-(o-halogenophenyl)-1,2,3-triazoles

Mesoaldehyde 1,3-dioxime was treated with either 2,4,6-trichlorophenyl- (a), o-fluorophenyl- (b), or o-bromophenyl- (c) hydrazine to give the corresponding mesoaldehyde 1,3-dioxime-2-halogenophenylhydrazones (1a,b,c). The latter were O-acetylated with acetic anhydride, and cyclized to triazole 4-oximes (3b, c) or triazole 4-O-acetyloximes ( 6a,b,c ) with cesium carbonate, then converted to nitriles ( 7a,b,c ) by refluxing with acetic anhydride followed by pyrolysis, or to aldehydes ( 4a,b,c ) by hydrolysis. The nitriles ( 7a,b,c ) were also converted to acids ( 9a,b,c ), esters ( 10a,b,c ), amides ( 8a,c ), an alcohol (11a), and an amine ( 12a ). In addition, tetrazoles of two types were prepared. The first ( 13d,e ) were obtained from the acid chlorides by the action of 5-aminotetrazole, whereas the second ( 14f ) was produced from the respective nitrile by the action of ammonium azide.     

The effect of crown ethers on the alkylation of a cyclic β-keto ester

The effects of crown ethers (6 and 7) on the reactions of sodium (2a) and potassium enolates (2b) of 2-ethoxycarbonylcyclohexanone (1) with isopropyl iodide in dimethylsulfoxide and dimethoxyethane have been investigated. When the addition of crown ether promoted dissociation of ion pair 2 in either of the two solvents, the total rate of reaction (k_t) increased and the ratio of carbon- (3) to oxygen-alkylation (4 and 5) products decreased. The results are consistent with the involvement of both the ion pair and more dissociated species in alkylation and with greater reactivity for the latter.     

高效液相色谱氮杂冠醚键合固定相的合成及性能研究

我们曾用γ－氯丙基键合硅胶（ＣＰＳ），在氢化钠（ＮａＨ）作用下合成了３－（氮杂－１８－冠－６）丙基键合固定相（ＢＣＰ）［１］．该固定相对碱基、核苷酸、硝基苯酚等有较好的分离选择性，但由于ＮａＨ对硅胶基质腐蚀作用较大，导致ＢＣＰ柱效及渗透性较低．本文采...