The Hydroxide‐Promoted Catalytic Hydrodefluorination of Fluorocarbons by Ruthenium in Aqueous Media

A ruthenium complex ligated by the non‐innocent protic ligand 2,6‐imidizoylpyridine (IPI) in aqueous potassium hydroxide media is shown to be a suitable catalyst for the C F bond activation and subsequent hydrodefluorination (and hydrogenolysis) of a model fluorocarbon. Furthermore, the conversion of C F bonds was enhanced upon increasing the concentration of potassium hydroxide [KOH]. A simple, non‐ligated heterogeneous analogue derived from ruthenium(III) trichloride trihydrate dissolved in aqueous potassium hydroxide is shown to be an even more active catalyst, capable of hydrodefluorination of aryl fluorocarbons at room temperature and alkyl fluorocarbons under more forcing conditions.     

水介质中有机合成反应的研究进展

近年来,水作为有机合成反应介质的报道相继出现。本文综述了水介质中几类有机合成反应的研究进展,这些反应类型包括还原、氧化、取代、加成、缩合、偶联等。     

碱性介质中对硝基苯氧乙醇的稳定性

选用对硝基苯氧乙醇这一芳香醚作为研究对象,研究了它在碱性介质中的醚键裂解情况。试验结果表明,碱的浓度越高、碱性越强、反应温度越高、反应时间越长、亲核试剂的活性越强,对硝基苯氧乙醇越不稳定,醚键断裂的程度越大,同时还发现有溶剂参与的现象。用高效液相色谱仪分析了对硝基苯氧乙醇的转化率。     

Studies on the Hydration Behavior of Polyvinyl Alcohol in Aqueous Solution: A Kinetic Approach through the Hydrolysis of Benzocaine

The present work investigates the structural and dynamical features of Polyvinyl alcohol (PVA) and surfactant–PVA system through the change in the rate of hydrolysis of benzocaine. The UV–Vis spectra of benzocaine showed that the absorbance values at λ_max (284 nm) increased with the increase in PVA. The rate of hydrolysis decreased in the dilute- and high-concentration regions of PVA, whereas it remains unchanged in the mid-concentration range of PVA, known as the polymer–polymer interaction region. These observations correspond to the structural changes in PVA with the increase in PVA concentration in aqueous solution. The aggregation behavior of PVA was further studied using transmission electron microscopy micrographs. The rate constant for the hydrolysis of benzocaine showed peaked behavior with the increase in [CTABr] in the CTABr-PVA mixed system. The sodium dodecyl sulphate (SDS) molecules modify the PVA chains into a more compact form, and so, the hydration number around PVA is decreased. Consequently, the less hydrophilic benzocaine entangles with SDS-PVA, whereas OH^– ions aggregate into the aqueous pseudophase, resulting in a decrease in the rate of hydrolysis in the SDS–PVA mixed medium. The calculated value of binding constant increased with the increase in PVA in both CTABr-PVA and SDS-PVA mixed systems.     

植物纤维在复合材料中的应用与发展

综述木纤维、麻纤维和竹纤维等纤维增强塑料复合材料的发展历史及现状,展望植物纤维增强塑料复合材料广阔的应用前景。     

Role of O3 and OH· Radicals in Ozonated Aqueous Solution for the Photoresist Removal of Semiconductor Fabrication

The role of direct oxidation by aqueous O₃ and advanced oxidation by OH^· in the removal of photoresist was studied by chemical kinetic simulation and experiments of O₃ reactivity and decomposition in homogeneous aqueous solutions. O₃ is the main species responsible for the removal of conventional photoresist in the ozonated water cleaning process, and the timing of initiator addition to ozonated water is important to maintain high O₃ concentration. Simulation using t-butanol implies that maintenance of a high OH^· concentration is required to remove highly implanted photoresists that O₃ itself cannot easily remove.     

钙土在橡胶中的应用研究

用不同改性剂及不同改性方法对钙土进行了改性实验．制备了钙土／丁苯橡胶复合材料,讨论了材料的力学性能及影响因素。添加适量的钙土．可以获得性能较好的产品,并能降低产品的成本。     

基于 MALDI-OF质谱探究水性聚氨酯分散体的扩链反应

为更加明确水性聚氨酯分散体的扩链反应机理,采用可水解的聚酯合成水性聚氨酯分散体,可控水解聚酯结构保留氨基甲酸酯结构和脲结构获得一系列水解片段,一些水解片段隐含了扩链反应的信息,采用 MALDI-TOF质谱分析水解片段的结构和组成,可以追溯扩链反应进程和分析扩链反应机理。研究发现预聚体端基结构不同,其反应产物存在较大差异,与亲水结构相连的预聚物的端异氰酸酯基（—NCO）大部分被水和二胺封端,而与疏水结构相连的—NCO端基大部分与水和二胺发生扩链反应。基于研究结果,提出了一种全新的扩链反应机理：扩链反应不仅发生在颗粒表面,也发生在颗粒内部。否定了扩链反应仅发生在颗粒表面的普遍看法。     

Effect of Polyelectrolyte Dispersants on the Preparation of Silica-Coated Zinc Oxide Particles in Aqueous Media

Sodium silicate was utilized to obtain a SiO₂ coating on ZnO particles to prevent a photocatalytic reaction between ZnO and phenol. During the coating process, pH control is important to avoid dissolution of the ZnO as well as to obtain a good dispersion. Two kinds of polyelectrolyte dispersants were used to control the surface charge of the ZnO particles in aqueous media. As a result, poly(ethylenimine) (PEI) shifted the isoelectric point of ZnO from pH 9 to pH 10, whereas poly(ammonium acrylate) (PAA) made the surface charge of ZnO negative between pH 6 and pH 11. The change in the ZnO surface charge produced by adding polyelectrolyte dispersants makes it possible to obtain uniform silica–coated ZnO particle in aqueous media. UV–irradiation experiments showed that PEI, which can make the surface charge opposite to that of SiO₂, is more effective in obtaining a thick silica coating on ZnO.     

生产硫酸铝反应釜内衬材料选择与实用工艺

介绍了硫酸铝反应釜内衬防腐材料的选择 ,并对复合内衬的材料及实用工艺进行了叙述     

Modulating the Aggregation Behavior of 1-Methyl-3-Octylimidazolium Chloride by Alcohols in Aqueous Media

The self-organization and aggregation behavior of a surface active ionic liquid (SAIL) 1-methyl-3-octylimidazolium chloride [C₈mim]Cl, was investigated in aqueous solutions of alcohols 1,2-propanediol and 1-propanol in different compositions using conductivity, surface tension and fluorescence measurements at room temperature. This surface active ionic liquid was synthesized by the reaction of 1-methylimidazole with 1-chlorooctane. Fluorescence spectroscopy was employed to get detailed insight into the local microenvironment of the aggregates, critical aggregation concentrations (CAC) and aggregation number (N _agg.). Degree of ionization (α), CAC and various thermodynamic parameters like the standard Gibbs free energy of aggregation (ΔG _agg. ⁰ ), standard enthalpy of aggregation (ΔH _agg. ⁰ ) and standard entropy of aggregation (ΔS _agg. ⁰ ) were calculated using conductivity measurements at different temperatures (288.15, 298.15 and 308.15 K). The surface activity of the IL in various mixed solvents was evaluated from surface tension measurements by calculating various surface parameters like the minimum surface area occupied by a single ionic liquid molecule (A _min), adsorption efficiency (pC ₂₀), maximum excess concentration at the surface (Γ _max), effectiveness of surface tension reduction(Π _CAC), surface tension at CAC (γ _CAC), p (packing parameter) and CAC at different compositions. Increases in the CAC values were observed with the increase in the amount of alcohols which is attributed to the balancing between electrostatic and hydrophobic interactions. The results from different techniques show that the CAC increases with increase in the amount of the alcohol which is due to the solubilization of the IL molecules which delays the aggregation process. This shows that the spontaneity of the aggregation process of IL decreases with the increase in the concentration of alcohols in water.     

Characterization of Phosphoranes Obtained by the Spontaneous Carbonyl-Catalyzed Phosphorylation of Monosaccharides and Polyols in Aqueous Media

Phosphorylation is a very important biochemical process in metabolism and biochemical marking. The mechanism for the biophosphorylation of substrates and the hydrolysis/transesterification of RNA has been suggested to proceed through phosphorane intermediates. Although the phosphorane intermediate/transition state has long been a subject of many theoretical models and studies, it has neither been isolated nor characterized, with most information derived from the hydrolysis and radiolabeling of cyclic phosphotriesters. We herein present the first report of the spontaneous phosphorylation of sugars and polyols in the absence of enzymes. That is, aldehydes and ketones combine with inorganic phosphates to form activated phosphates that phosphorylate alcohols without the requirement of any enzyme or additional activating agent. This phosphorylation is particularly favored in polyhydroxycarbonyls that can form internal cyclic acetals to give rise to the corresponding acetal phosphoranes. We have further characterized these phosphoranes and demonstrated their dehydration to the corresponding phosphates by using high-resolution mass spectroscopy. The phosphorylation of adenosine and uridine to form the corresponding phosphoranes was also achieved.     

铀酰配合物高效识别水溶液中Fe3+的性质研究

基于含氮的柔性三羧酸配体异氰脲酸三(2-羧乙基)酯(H3tci),合成了一个具有二维空间结构的铀酰配合物(UO2(tci)·2H2O),通过X射线单晶衍射的方法测定了其晶体结构.在水溶液中,研究了该铀酰配合物对过渡金属离子的荧光作用,结果显示,该配合物对Fe3+有较好的敏感性.进一步的探索实验表明,该配合物可以高选择性...     

机械类专业开展材料类毕业设计课题的思考

毕业设计是培养学生创新能力的重要手段.结合实际情况,在机械类专业开展了材料类课题毕业设计。根据毕业设计结果,提出了一些思考和建议。     

The Application of a Recyclable Organocatalytic System to the Asymmetric Domino Michael/Henry Reaction in Aqueous Media

A new type of pyrrolidine‐based organocatalyst has been developed and found to be very effective for the domino Michael/Henry reaction in aqueous solvents. For the reaction involving pentane‐1,5‐dial and various nitroolefins, good yields (65–85%) and excellent enantioselectivities (99%) were obtained using this catalyst. In addition, the catalyst could be recycled up to four times resulting in good yields and up to seven times with good enantioselectivity.     

一种新型重氮萘醌感光剂用于阳图PS版的性能研究

重氮萘醌体系阳图PS版因具有感度高、上墨快、显影简单、环保以及储存稳定性好等特点,一直在印刷领域处于重要地位。随着印刷业的发展,还应进一步提高阳图PS版的感度,提高耐溶剂(异丙醇)性、耐印力。本文主要介绍了一种新型的用于阳图PS版的重氮萘醌系感光剂的合成方法和其成像性能的研究。这种感光剂是由6,7-二羟基-3,3-二苯基-3H-苯并呋喃-2-酮作为酯化母体,按照一定的摩尔比与2,1,5-重氮萘醌磺酰氯进行酯化反应制得。它与线性酚醛树脂、有机溶剂等成分组成配方。通过配方实验对这种新型感光剂的成像性能进行了研究,发现其不仅显影宽容度大,而且具有较高的感度,较好的抗碱留膜率和耐溶剂性能,良好的分辨率,并对其作为PS版感光剂的应用前景进行了评价。     

Evaluation of the contribution of lignin stilbene phenol units in the photoyellowing of peroxide-bleached lignin-rich pulps

In order to assess and quantify the contribution of stilbene phenols in photoreversion of bleached high-yield pulps, a method to reduce the stilbene double bond and quantify the formed diphenylethane was developed on 4-benzyloxy-3,3′-dimethoxy-4′-hydroxystilbene, as lignin monomer model, and also on a more sophisticated lignin polymer model constituted by a polystyrene framework containing 4,4′-dihydroxy-3,3′-dimethoxystilbene elements as pendent groups. The method used RhCl(PPh₃)₃ as soluble catalyst to get an efficient hydrogenation and AlCl₃ in benzene to liberate the diphenylethane from the polymer framework. For the first time a semiquantitative evaluation of the content of the stilbene phenols formed from β-1 units was given for high-yield pulps. The value of 2 p-stilbene phenols for 1000 C₉ lignin units found indicates that they are present in very small quantities after the peroxide bleaching. UV irradiation of the polystyrene model adsorbed on solid cellulose matrix had revealed an efficient stabilization after the hydrogenation treatment. This was not the case for the peroxide bleached pulp showing that the p-stilbene phenols formed from β-1 units are not the main contributors of the rapid yellowing of bleached lignin-rich pulps. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2517–2531, 1998     

Concentration profiles of reactant in a viscous finger formed during the interfacially reactive immiscible displacements in porous media

A simple unsteady-state convective-diffusion model was employed to simulate reactant concentration profiles in a viscous finger, which is created during interfacially reactive displacement of two immiscible fluids in porous media. A two-dimensional system was considered. It was assumed that the finger grew in one direction at a constant flow rate and that a fast chemical reaction was taking place at the oil–water interface layer. Interaction with reservoir rock was also taken into account. Two types of convective flow were studied: steady-state laminar flow with a parabolic velocity profile and plug flow with a flat velocity profile. The numerical method of lines was used to solve the model equation. A significant decrease of reactant concentration in the water phase, especially in the fingertip area was observed. This can cause important changes in interfacial behavior and influence the efficiency of fluid displacement. The model numerically confirmed previous visual observations of displacing patterns during the displacement of acidified oil by alkaline solutions.     

含能化合物的超分子化学研究进展

介绍了以环糊精、碳纳米管、石墨烯、介孔材料为超分子主体的主-客体含能复合物以及共结晶含能材料的最新研究进展,指出了用环糊精制备超分子含能复合物的缺陷,分析了碳纳米管、石墨烯、介孔材料用于制备高能钝感超分子含能复合物及共结晶含能材料的可行性和研究方法,展望了超分子化学方法在含能材料领域的应用前景。附参考文献54篇。     

Anodic growth of passive layers on steel rebars in an alkaline medium simulating the concrete pores

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques have been used to study passive layers anodically grown on steel rebars in an aqueous alkaline solution simulating the electrolyte of the concrete pores. Nyquist diagrams recorded by EIS at the different stabilization potentials show a diffusional tail at low frequencies. The analysis of the impedance measurements has been made by means of an equivalent circuit with a Warburg component and within the framework of the point defect model (PDM) theory. It is observed that the calculated concentration of vacancies is a function of the potential in accordance with the theoretical prediction of the PDM.