丙烷选择氧化的铋钼复合氧化物催化剂结构和催化性能

 应用X射线衍射（XRD）,傅里叶变换激光拉曼光谱（FT－LRS）和微型催化反应装置等测试手段研究了丙烷选择氧化的Bi－Mo复合氧化物催化剂的结构和催化性能．结果表明,Bi组分是丙烷催化氧化脱氢为丙烯的主要活性组分,而丙烯醛选择性的大小与Bi－Mo复合氧化物催化剂的组成和结构密切相关．不同组成的Bi－Mo复合氧化物催化剂在丙烷转化率（～28．0％）相近的情况下,其丙烯醛选择性随Mo／（Mo＋Bi）原子比的增加先逐渐增加,在Mo／（Mo＋Bi）原子比为0．50时达极大值（～28．1％）．随Mo／（Mo＋Bi）原子比进一步增加,丙烯醛选择性又急剧下降．XRD和FT－LRS结果表明,Bi2O3和MoO3之间可形成二元Bi－Mo－O晶相固溶体,从而显著提高了催化剂对选择氧化反应的催化性能．尤其是当α－Bi2（MoO4）3和γ－Bi2MoO6两相共存时,Bi－Mo复合氧化物催化剂具有较优良的选择氧化催化性能．γ－Bi2MoO6参与了α－Bi2（MoO4）3对丙烷的选择氧化,加速了选择氧化活性氧物种的再生．     

Nickel-Catalyzed Sulfonylation of Aryl Bromides Enabled by Potassium Metabisulfite as a Uniquely Effective SO2 Surrogate

The development and mechanistic investigation of a nickel-catalyzed sulfonylation of aryl bromides is disclosed. The reaction proceeds in good yields for a variety of substrates and utilizes an inexpensive, stench-free, inorganic sulfur salt (K₂S₂O₅) as a uniquely effective SO₂ surrogate. The active oxidative addition complex was synthesized, isolated, and fully characterized by a combination of NMR spectroscopy and X-ray crystallography analysis. The use of the isolated oxidative addition complex in both stoichiometric and catalytic reactions revealed that SO₂ insertion occurs via dissolved SO₂, likely released upon thermal decomposition of K₂S₂O₅. Key to the success of the reaction is the role of K₂S₂O₅ as a reservoir of SO₂ that is slowly released, thus preventing catalyst poisoning.     

NMR法研究Na+在二元混合溶剂中的溶剂化

~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-aceton,water-ace- tonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF,methanol-ben- zene, and methanol-dioxane were measured.By means of iso-solvation point the solvating abilities were compared as water>aceton≥acetonitrile≥ethanol and DMF>methanol. The preferential solvation free energies of Na~+ for the pairs of solvents, methanol-DMFand water-aceton,were evaluated as -2.7 kJ mol~(-1) for DMF to methanol and 4.6 kJ mol~(-1) for aceton to water.~(23)Na~+ chemical shift in methanol-benzene is independent of the content of benzene. It verifies the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The inewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.     

Lorentz序列空间的装球问题

Ｂａｎａｃｈ空间中装球问题的研究，近四十年来已取得了令人瞩目的发展。Ｂａｎａｃｈ空间的装球值的范围已经确定，Ｌ＿ｐ空间及Ｏｒｌｉｃｚ序列空间Ｉ＿Ｍ等许多经典Ｂａｎａｃｈ空间装球值已经找到．本文研究又一类经典Ｂａｎａｃｈ空间──Ｌｏｒｅｎｔｚ序列空间的装球问题，给出了Ｌｏｒｅｎｔｚ序列空间的装球值。     

Dispersion state and catalytic properties of vanadia species on the surface of V<Subscript>2</Subscript>O<Subscript>5</Subscript>/TiO<Subscript>2</Subscript> catalysts

The dispersion state and catalytic properties of anatase-supported vanadia species are studied by means of X-ray diffraction (XRD), laser Raman spectroscopy (LRS), H₂ temperature-programmed reduction (TPR) and the selective oxidation of o-xylene to phthalic anhydride. The almost identical values of the experimental dispersion capacity of V₂O₅ on anatase and the surface vacant sites available on the preferentially exposed (001) plane of anatase suggest that the highly dispersed vanadium cations are bonded to the vacant sites on the surface of anatase as derived by the incorporation model. When the loading amount of V₂O₅ is far below its dispersion capacity, the dispersed vanadia species might mainly consist of isolated VO_x species bridging to the surface through V-O-Ti bonds. With the increase of V₂O₅ loading the isolated vanadia species interact with their nearest neighbors (either isolated or polymerized vanadia) through bridging V-O-V at the expenses of V-O-Ti bonds, resulting in the increase of the ratio of polymerized to isolated vanadia species and the decrease of the reactivity of the associated surface oxygen anions and, consequently, although the activity increases with loading to reach a maximum value, the turn over number (TON) of the V₂O₅/TiO₂ catalyst decreases linearly. When the loading amount of V₂O₅ is higher than its dispersion capacity, the turn over number decreases more rapidly with the increase of V₂O₅ loading due to the formation of V₂O₅ crystallites in which the oxygen anions associated with V-O-V bonds are less reactive and only partially exposed on the surface.     

Sacrificial-Template-Assisted Syntheses of Aluminate and Titanate Nanonets via Interfacial Reaction Growth

Crystalline FeAlO₃/FeAl₂O₄ nanonets were synthesized by a modified template-assisted approach using anodic aluminum oxide (AAO) as a reactive and sacrificial template to direct and promote interfacial reaction growth (IRG). The as-prepared nanonets replicate the morphology of the porous AAO template and contain mixed FeAlO₃ and FeAl₂O₄. To extend the applicability of the sacrificial-template-assisted IRG approach, porous anodic titanium oxide (ATO) was used as template in place of AAO, giving rise to Zn₂TiO₄ nanonet/nanotube and PbTiO₃ nanonet/nanotube. These latter products are polycrystalline due to the polycrystalline nature of the ATO template. Growth mechanism for the formation of the Zn₂TiO₄ and PbTiO₃ nanostructures is proposed. The present study shows that the IRG approach can be extended to fabricate patterned complex oxide nanomaterials that may find applications in a wide range of nanotechnologies such as electronics, photonics and spintronics.     

Cyclopropanation of active methylene compounds with β-alkoxycarbonyl vinylsulfonium salts

An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tentative reaction mechanism was proposed.     

High-throughput logP measurement using parallel liquid chromatography/ultraviolet/mass spectrometry and sample-pooling

A novel approach to high-throughput logP measurement based on liquid chromatography/ultraviolet/mass spectrometry (LC/UV/MS) is proposed. The logP value is determined by correlation with the logk value, where k is the capacity factor k = (t(r)-t(0))/t(0), with the logP value using a defined set of standards. Since the analyte retention time (t(r)) is determined from the appropriate extracted ion chromatogram (EIC), there are no interferences from impurities and this allows the pooling of multiple compounds into one injection. To ensure the accuracy and instrument robustness in a routine high-throughput environment, a simple and MS-friendly mobile phase consisting of 20 mM ammonium carbonate (pH 8.0) for basic compounds or 20 mM ammonium formate (pH 1.0) for acidic compounds, both in combination with methanol at a ratio of 45:55, is used. This approach has been successfully used on single as well as parallel multi-channel LC/UV/MS systems to screen small to large sets of lead compounds and their analogs. A high-throughput capability to analyze over 1000 compounds per day has been achieved.