非化学计量组成Ba1.03Ce0.5Zr0.4La0.1O3－α的化学稳定性和离子导电性

用高温固相反应法合成了非化学计量组成的Ba_1.03Ce_0.5Zr_0.4La_0.1O_{3－α质子导体. 粉末X射线衍射(XRD)结果表明, 该材料为单一钙钛矿型BaCeO3斜方晶结构, 在高温下、CO2或水蒸气气氛中具有较高的稳定性. 扫描电子显微镜(SEM)观察分析表明, 材料经1550 ℃烧结20 h非常致密. 在500～900 ℃温度范围内, 用交流阻抗谱技术测定了材料在湿润氢气和湿润空气气氛中的电导率; 用气体浓差电池方法测定了材料在湿润氢气、湿润空气气氛中和氢-空气燃料电池条件下的离子迁移数, 研究了材料的离子导电特性, 并与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料进行了比较. 结果表明, 在500～900 ℃温度范围内、湿润氢气气氛中, Ba1.03Ce0.5Zr0.4La0.1O3－α材料的质子迁移数为1, 是一个纯质子导体. 在湿润空气气氛中, 材料的氧离子迁移数为0.688～0.170, 质子迁移数为0.218～0.017, 是一个氧离子、质子和电子空穴的混合导体. 在氢-空气燃料电池条件下, 材料的离子(氧离子＋质子)迁移数为0.990～0.796, 是一个氧离子、质子和电子的混合导体. 与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料相比较, 在相同实验条件下非化学计量组成的Ba1.03Ce0.5Zr0.4La0.1O3－α材料具有较高的电导率和离子迁移数.}     

BrΦnsted酸性离子液体[HSO3-bpy][HSO4]催化合成β-吲哚酮

以BrΦnsted酸性离子液体[HSO3-bpy][HSO4]为催化剂, 将吲哚或取代吲哚与α,β-不饱和酮在乙腈中于80 ℃下反应3 h, 以92%～98%的产率制备了一系列的β-吲哚酮. 该方法简便易行且产率高. 催化剂离子液体对环境友好, 并可循环使用.     

An efficient synthesis of benzofuran derivatives under conventional/non-conventional method

<正>l-Methyl-3-ethyl imidazolium bromide[meim]Br/basic alumina(Al_2O_3) has been found to promote the cyclocondensation of chloroacetone/chloroethyl acetate with salicylaldehydes under conventional as well as microwave irradiation to yield benzofuran derivatives.     

硅花园法合成硅酸铝质子酸

A series of aluminasilicate Br?nsted acid catalysts were synthesized with the “silica garden” method, and characterized with XRD, XPS and NH₃-TPD technique. Acid center concentration was measured using ionic ex-change method. The catalytic activities for cumene cracking of the silica garden Br?nsted acid catalysts were ob-served and compared to that of zeolite HY and traditional acidic aluminasilicate catalysts. It was found that the 6-coordinate and 4-coordinate aluminum atoms were in silica garden Br?nsted acid catalysts. There were two kinds of acid centers and a little of crystal in silica garden Br?nsted acid catalysts. And it was also found that the crystal increased the acidities of the catalysts. The catalytic activity and strong acid center concentration of the silica garden Br?nsted acid catalysts were between that of zeolite HY and traditional acidic aluminasilicate catalysts.     

A convenient and efficient method for incorporation of pentafluorosulfanyl (SF5) substituents into aliphatic compounds

Both SF₅Cl and SF₅Br undergo smooth, high yield addition to alkenes and alkynes under the mild free radical chain reaction conditions of triethylborane initiation at low temperature, although the SF₅Br chemistry is somewhat limited by its competing high electrophilic reactivity with electron rich alkenes. The SF₅Cl addition reaction is relatively insensitive to a wide variety of non-allylic functionalities.     

Probing the surface acidity of modified γ-alumina with1H and15N high-resolution solid state NMR spectroscopy

¹H MAS NMR and¹⁵N NMR studies of adsorbed N₂ and N₂O molecules were used to characterize Br?nsted and Lewis acidic sites of unmodified γ-Al₂O₃ and γ-Al₂O₃ modified with NaOH. Changes in the concentrations of surface hydroxyls with the increase in the number of more “basic” OH groups for NaOH/γ-Al₂O₃ have been found by¹H MAS NMR experiments. Two different types of Lewis acidic sites in γ-Al₂O₃ have been revealed using¹⁵N NMR studies. The strongest sites are poisoned even at small NaOH concentrations (ca. 0.05 wt.%). Not only the number of electron-accepting sites but also their strength are supposed to decrease for modified γ-alumina.     

Ab initio study on the reaction mechanism of ozone with bromine atom

Ab initio calculations of the potential energy surface (PES) for the Br+O₃ reaction have been performed using the MP2, CCSD(T), and QCISD(T) methods with 6‐31G(d), 6‐311G(d), and 6‐311+G(3df). The reaction begins with a transition state (TS) when the Br atom attacks a terminal oxygen of ozone, producing an intermediate, the bromine trioxide (M), which immediately dissociates to BrO+O₂. The geometry optimizations of the reactants, products, and intermediate and transition states are carried out at the MP2/6‐31G(d) level. The reaction potential barrier is 3.09 kcal/mol at the CCSD(T)/6‐311+G(3df)//MP2 level, which shows that the bromine atom trends intensively to react with the ozone. The comparison of the Br+O₃ reaction with the F+O₃ and Cl+O₃ reactions indicates that the reactions of ozone with the halogen atoms have the similar reaction mechanism. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

有机反离子对C12-s-C12·2Br水溶液表面活性的影响

溶液中添加的苯磺酸钠(SNzS)和萘磺酸钠(SNphS)与C12-s-C12·2Br产生强烈结合, 增大了Gemini表面活性剂分子的疏水性, 明显促进其在气/液界面的吸附和在溶液中的聚集. 这使得体系降低水表面张力的效率和能力大大提高, 并且在表面活性剂浓度很低时就生成了小聚集体. 因而, 此时表面张力法测得的cmc仅具有表观上的意义, 只反映了表面活性剂在气/液界面达到饱和吸附时的临界浓度. SNphS的疏水性强于SNzS, 更有效地促进了C12-s-C12·2Br的吸附和聚集.     

Tetraaryl-1,3-dioxolane-4,5-dimethanols as catalysts for the addition of trimethylsilyl cyanide to benzaldehyde and the oxirane ring

The synthesis of 1,2-, 1,3-, and 1,4-phenylene-bis[(4R,5R)-4,5-di(hydroxydiphenylmethyl)-1,3-dioxolane]s (ortho-, meta-, and para-bis-(R,R)-TADDOLs) and bis[4-{[(4R, 5R)-4,5-di(hydroxydiphenylmethyl)]-1,3-dioxolan-2-yl}phenyl]methane was carried out. The possibilities of the use of these compounds as catalysts for the C-C bond formation in the addition of Me₃SiCN to benzaldehyde and the oxirane ring opening in cyclohexene oxide by Me₃SiCN were investigated. The catalytic activity of different bis-(R, R)-TADDOLs in this series depends on their structure. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1451–1458, August, 2007.     

Synthese und Kristallstruktur der molekularen Clusterverbindung W6Br14

Synthesis and Crystal Structure of the Molecular Cluster Compound W₆Br₁₄ Brownish-black crystals of W₆Br₁₄ are formed in the direct synthesis from W₆Br₁₂ and Br₂ (400 K). The compound crystallizes cubically with neutral cluster molecules ([W₆Br]Br): a = 13.458 Å; Pn3 (Nr. 201); d?(W? W) = 2.653 Å; d?(W? Brⁱ) = 2.616 Å; d?(W? Br^a) = 2.569 Å. The W atoms are 0.03 Å outside of the Br cube faces. The molecules are arranged according to a cF point configuration, but each is rotated ?23° about a threefold axis in order to avoid short inter cluster distances Br^a? Br^a. Nevertheless, via 12 short intermolecular distances per cluster of about d(Brⁱ …? Br^a) = 3.487 Å the clusters are interconnected by forming two independent and interpenetrating 3D nets (Cu₂O type). Although local distortion of the M₆X cluster does not occur, as is expected for this system with 22 electrons per M₆ octahedron, it is assumed that the Jahn-Teller theorem is fulfilled collectively via the low-symmetry nets of intermolecular interactions.