痕量钒的分析进展

综述近年来测定痕量钒的主要方法,包括光度法如常规光度法、流动注射光度法、催化动力学光度法、萃取光度法、导数光度法以及原子吸收法、荧光法、交流示波极谱法、催化动力学离子选择电极法和流动注射化学发光法等。     

四苯基苯基五苯基苯基二乙氧基硅烷的分离制备和鉴定

杜作栋等先后合成了四苯基苯基有机硅化合物和五苯基苯基有机硅化合物,并用溶剂沉淀法和重结晶法纯化产物后进行结构分析,在此基础上陈剑华等又合成了双多苯基苯基有机硅化合物,此类化合物具有更好的耐高温性能,可制成耐高温树脂、耐高温橡胶、耐高温粘合剂和耐高温涂料。     

Ultraviolet photolysis of CH2I2 in methanol: O-H insertion and HI elimination reactions to form a dimethoxymethane product

Ultraviolet photolysis of low concentrations of CH2I2 in methanol solution found that CH2I2 is converted into dimethoxymethane and some H+ and I- products. Picosecond time-resolved resonance Raman (ps-TR3) experiments observed that the isodiiodomethane (CH2I-I) photoproduct decayed faster as the concentration of methanol increases, suggesting that isodiiodomethane is reacting with methanol. Ab initio calculations indicate isodiiodomethane is able to react with methanol via an O-H insertion/HI elimination to form an iodoether (ICH2-O-CH3) and HI products. The iodoether can then further react via another O-H insertion/HI elimination reaction to form the dimethoxymethane (CH3-O-CH2-O-CH3) observed in the photochemistry experiments. A reaction mechanism consistent with these experimental and theoretical observations is proposed.     

Comparison of the dehalogenation of dihalomethanes (CH2XI, where X = Cl, Br, I) following ultraviolet photolysis in aqueous and NaCl saltwater environments

The ultraviolet photolysis of low concentrations of CH(2)XI (X = Cl, Br, I) were investigated in water and saltwater solutions by photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both kinds of solutions formed mostly CH(2)(OH)(2) and HI and HX products. However, photolysis of the CH(2)XI molecules in saltwater resulted in production of some CH(2)XCl products not observed in aqueous solutions without salt present. The appearance of these new products in saltwater solutions is accompanied by a decrease in the amount of CH(2)(OH)(2), HI, and HX products compared to photolysis in aqueous solutions without salt present. The possible implications for photolysis of CH(2)XI and other polyhalomethanes in seawater and other salt aqueous environments compared to nonsaltwater solvated environments is briefly discussed.     

LIGHT-SCATTERING STUDY OF POLYELECTROLYTE HOLLOW CAPSULES

Silver halide (AgX) microcrystal was used as template to synthesize hollow polyelectrolyte capsules. These hollow capsules were characterized by laser light scattering (LLS) used to measure the size of the capsules in solution. The ratio of hydrodynamic radius (Rh) from dynamic LLS to the radius of gyration (Rg) from static LLS is almost unity, revealing that the entities are hollow in solution. The results suggest that the LLS method can be regarded as a good complement to the confocal laser scanning microscopy (CLSM) method for the characterization of small hollow capsules, and it possesses the advantage of not needing fluorescence labeling.     

CuCl_2-CuI体系对苯胺氧化乙氧羰基化生成苯基氨基甲酸乙酯反应的催化作用

本文发现并研究了CuCl_2-CuI体系对苯胺氧化乙氧羰基化生成苯基氨基甲酸乙酯反应的催化作用,考察了各种反应条件对催化剂性能的影响,用测定转化数的方法研究了催化剂的稳定性。单独使用CuCl_2或CuI作为催化剂时,催化活性很低,两者同时使用时,催化活性明显提高。副产物是苯胺氧化偶联反应生成的偶氮苯,反应开始时,主要生成偶氮苯,随着反应的进行,目的产物苯基氨基甲酸乙酯的比例增加,提高反应温度有利于目的产物的生成。     

二甲基甲酰胺中四种钕盐的电导

通过电导测量研究了四种钕盐：Nd(CF3SO3)3、Nd(ClO4)3、Nd(NO3)3和NdCl3在极性非质子溶剂DMF中的电导性质.利用线性拟合方法求得在25 ℃下Nd(CF3SO3)3和Nd(ClO4)3的极限摩尔电导率分别为278.8和 280.7 S•cm2•mol－1.用间接方法求得Nd(NO3)3 与NdCl3 的极限摩尔电导率分别为297.2和287.3 S•cm2 •mol－1.在25～65 ℃温度范围内，Nd(CF3SO3)3和Nd(ClO4)3的电导率随温度呈线性变化. Nd(NO3)3和NdCl3的电导行为表现出明显的离子缔合.     

成都市土壤-植物系统铅污染状况初步研究

为研究成都市土壤-植物系统铅污染状况，分析了成都市五种蔬菜及其根系土的铅含量。结果表明，土壤铅含量变化范围61．0～115．0mg/kg，均值为77．3mg/kg，所有样品含量均超过成都市土壤环境背景值，以城东和城南污染最为严重；蔬菜中铅含量以莴笋叶最高，萝卜最低，叶菜类高于瓜果类；蔬菜污染严重区与土壤污染区差别明显，说明土壤铅和植物铅污染源不同。     

V-Ag-Ni系氧化物的表面氧性质与甲苯选择性氧化的催化性能

制备了一系列Ｖ，Ａｇ，Ｎｉ原子比不同的三元氧化物，应用ＴＰＤ－ＭＳ技术研究了样品表面氧的性质，并测定了甲苯选择性氧化生成苯甲醛的催化活性。实验结果表明，样品表面存在有多种吸附的氧物种。在脱附温度＜９００℃：当Ｎｉ含量对Ａｇ（或Ｖ）的原子比为０．２５或０．５０时，仅在低温处出现有表面的Ｏ＾－和Ｏ＾２＾－两种氧物种的脱附峰；当Ｎｉ含量对Ａｇ（或Ｖ）的原子比增高到＞０．７５时，除有表面的Ｏ＾－和Ｏ＾２＾     

Synthesis and characterization of perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl end-capped styrene oligomers

Styrene oligomers with perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl end-groups have been synthesized with moderate to high yields (52-97%) via radical oligomerization by using perfluoro[2-(2-fluorosulfonyl)ethoxy]propyonyl peroxide (PPP) at various reactant ratios of styrene over PPP (80, 160, 240, 300, 360 and 420) and different temperatures (33, 37 and 42 °C), and characterized by FTIR, ¹H NMR and ¹⁹F NMR. The molecular weight of the oligomers measured by gel permeation chromatography (GPC) is dependent on the reactant ratio and reaction temperature. The polydispersity of the oligomers varies from 1.99 to 3.30. The oligomer obtained at the reactant ratio of 300 has the maximum yield (97%) and much broader polydispersity (3.30). The contact angles of water, θ_H2O, on the oligomer films are much bigger than that of polystyrene (PS). The glass transition temperature of the oligomers, T_g, increases with the increase of molecular weight and is lower than that of the parent polymer.