Fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF4 and XeF2

The selective fluorolactonization was achieved by treatment of cis-5-norbornene-2,3-endo-dicarboxylic acid or its monomethyl and dimethyl esters with F-TEDA-BF₄ or XeF₂. The reactions of 5-norbornene-endo-2-carboxylic acid and its monomethyl ester with F-TEDA-BF₄ or XeF₂ proceed in a non-selective manner to give fluorolactonization, addition and rearrangement products. The basic factor responsible for selectivity of the fluorolactonization is the presence of two endo-oriented carboxyl groups in the substrate molecule. The electrophilicity and type of the fluorinating agent is of secondary importance in this regard. It is postulated that the fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF₄ or XeF₂ is realized mainly via “open” fluoronorbornyl carbocation intermediates which in the reaction with XeF₂ are postulated as the tight ion pairs.     

Fluorination of activated aromatic systems with Selectfluor™ F-TEDA-BF4 in ionic liquids

Selectfluor™ was shown to be soluble in ionic liquid, thus allowing the ‘green’ electrophilic fluorination of activated aromatic systems compounds in high chemoselectivity and yields.     

Solubility of CO2 in imidazolium-based tetrafluoroborate ionic liquids

The solubility of CO₂ in imidazolium ionic liquids (ILs), 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF₄]), 1-hexyl-3-methyl imidazolium tetrafluoroborate ([hmim][BF₄]) and 1-octyl-3-methyl imidazolium tetrtafluoroborate ([omim][BF₄]) was determined at 305-25 K and pressures from 1 to 9 MPa. The influence of chain length of alkyl substituents on the imidazolium cation on the solubility of CO₂ was investigated. The differences in solubility with chain length are in the sequence [omim][BF₄] > [hmim][BF₄] > [bmim][BF₄]. The solubility data were correlated by the extended Henry's law, and enthalpy, Gibbs free energy and entropy changes were obtained.     

Direct iodination of indanone and tetralone derivatives by elemental iodine activated by Selectfluor™ F-TEDA-BF4

Derivatives of indan-1-one and 3,4-dihydronaphthalen-1(2H)-one bearing hydroxy or methoxy substituent on the aromatic ring were efficiently iodinated regioselectively at the α carbonyl position using elemental iodine activated by 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™ F-TEDA-BF₄) in methanol.     

Highly porous LiMnPO4 in combination with an ionic liquid-based polymer gel electrolyte for lithium batteries

A porous well defined LiMnPO₄ cathode material is synthesized by a sol-gel method. The electrochemical performance of the cathode material is evaluated in a cell with an ionic liquid-based polymer electrolyte (0.5 M LITFSI in EMImTFSI) and a lithium metal electrode. The results are compared to a cell with a traditional organic carbonate-based electrolyte (1 M LiPF₆ in EC/DMC). The cell with the ionic liquid-based polymer electrolyte presents an enhanced electrochemical intercalation performance of lithium ions, a high electrochemical stability window of 5 V, and an excellent cycling ability as compared with the organic based counterpart. Furthermore, the ionic liquid-based polymer gel electrolyte effectively prevents the dissolution of manganese — otherwise a common problem.     

Supramolecular aggregation in new crystals with nonlinear optical properties: 2-aminophenol-HClO4, 3-aminophenol-HClO4 and 4-aminophenol-HClO4

Three new hybrid crystals of 2-aminophenol-HClO₄ (2-AP-HClO₄, 1), 3-aminophenol-HClO₄ (3-AP-HClO₄, 2) and 4-aminophenol-HClO₄ (4-AP-HClO₄, 3) were obtained and their crystal structures determined. The 1 crystallises in centrosymmetric space group C2/c of monoclinic system while the other two (2 and 3) crystallise in the non-centro symmetric space group P2₁ and P2₁2₁2₁, respectively. The oppositely charged units of the crystals, i.e. positively charged 2-APH⁺, 3-APH⁺ and 4-APH⁺ and ClO₄⁻, interact via weak N⁺–HO and O–HO hydrogen bonds forming 3D-supramolecular network. Relative to KDP the SHG efficiencies are 0.62 for 2 and 0.33 for 3, measured at 1064 nm using the Kurtz–Perry method.     

Osmium catalyzed asymmetric dihydroxylation of methyl trans-cinnamate in ionic liquids, followed by supercritical CO2 product recovery

In this work, osmium-catalyzed asymmetric dihydroxylation (AD) of methyl trans-cinnamate was studied. Osmium and chiral ligand catalysts were immobilized in ionic liquid only, without any other reaction solvents, while the recovery of the product was performed by extraction with supercritical CO₂, and compared with results obtained by extractions with organic solvents such as hexane and diethyl ether. In supercritical CO₂ extraction experiments, optimal extraction pressure was found and ionic liquid chosen, so that the highest reaction yields coupled with lowest osmium content in the crude product can be achieved. Finally, recycle experiments of the same (ionic liquid + catalytic system) mixture were successfully conducted. Application of ionic liquids and supercritical CO₂ in osmium catalyzed AD allows for the isolation of the diol basically without contamination with osmium, in high yield and enantiomeric excess, and it makes possible the efficient reuse of ionic liquid solvent and the catalytic system.     

MgAl2O4尖晶石对锂离子电池正极材料LiMn2O4的循环性能影响研究

MgAl₂O₄ spinel doping into cathode materials LiMn₂O₄ was used to improve the cyclic performance of the cathode. X-ray analysis results showed, when MgAl₂O₄ precursors were mixed with LiMn₂O₄ and sintered at 770 ℃ for 12 hour, MgAl₂O₄-LiMn₂O₄ mulriple spinel with the same physical characteristics as pure LiMn₂O₄ were synthesized. The electro-chemical performance testing showed, comparing with pure LiMn₂O₄, the first charge-discharge capacity of doping materials somewhat reduced, but the cyclic performance improved. The mechanism for doping material was also discussed.     

An efficient one pot method for synthesis of carboxylic acids from nitriles using recyclable ionic liquid [bmim]HSO4

Environmentally benign ionic liquid [bmim]HSO₄ was found suitable for conversion of nitriles into carboxylic acids under mild conditions with excellent purity.     

一维纳米Co_3O_4,Ag/Co_3O_4及CuO/Co_3O_4的合成与电催化性能(英文)

采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。     

对BiVO4/BiPO4复合物可见光催化活性提高的研究

采用水热法合成出具有不同V、P物质的量之比的BiVO₄/BiPO₄复合物.n_V/n_P分别为:0.1/9.9、0.5/9.5、1/9、3/7、5/5.采用 XRD、FE-SEM、EDS、拉曼、可见光光度计、漫反射以及电化学等测试手段对BiVO₄/BiPO₄复合物进行表征.在可见光条件下降解亚甲基蓝来评价BiVO₄/BiPO₄复合物的光催化活性.结果显示,当n_V/n_P<3/7的时候,BiVO₄/BiPO₄复合物的光催化活性随着BiVO₄含量的增加而增加,当n_V/n_P=3/7的时候,复合物具有最佳的光催化性能,反应速率常数k为0.005 1 min^-1,是纯BiPO₄的23.2倍.BiVO₄/BiPO₄复合物的光催化机制主要是由于BiVO₄的加入,提高了电子-空穴的分离率,进而提高了光催化活性.     

Solubility of selected dibasic carboxylic acids in water,in ionic liquid of [Bmim][BF4], and in aqueous [Bmim][BF4] solutions

The solubilities of three dibasic carboxylic acids (adipic acid, glutaric acid, and succinic acid) in water, in the ionic liquid of 1-butyl-3-methyl-imidazolim tetrafluoroborate ([Bmim][BF₄]), and in the aqueous [Bmim][BF₄] solutions have been measured by a solid-disapperance method. The binodal curve of water + [Bmim][BF₄] was also determined experimentally from solid–liquid–liquid coexistence temperature up to near the upper critical solution temperature. Experimental results showed that each acid-containing binary behaved as a simple eutectic system. The solid–liquid equilibrium (SLE) data were correlated with the NRTL model for each binary system. The NRTL model with these determined binary parameters predicted the solid-disappearance temperatures of the aqueous ternary mixtures containing [Bmim][BF₄] and the dibasic acids to within an average absolute deviation of 2.0%.     

Alkylsulfate-based ionic liquids to separate azeotropic mixtures

The knowledge of liquid–liquid equilibria (LLE) of the ternary systems (hexane or heptane + ethanol + 1-ethyl-3-methylimidazolium ethylsulfate (EMIM EtSO₄)) is essential for the separation of alkanes from their azeotropic mixtures with ethanol. The experimental LLE have been determined at 298.15 K and atmospheric pressure. Experimental LLE are correlated using NRTL equation. The solvent capacity of the IL is compared with others aiming to analyze the efficiency of these molten salts used as entrainers. The extraction processes with this IL are simulated using conventional software. A comparison of the alkylsulfate-based IL's ability for the extraction process, determined from the simulation results, is enclosed.     

Magnetic diphase nanostructure of ZnFe2O4/γ-Fe2O3

Magnetic diphase nanostructures of ZnFe₂O₄/γ-Fe₂O₃ were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe₂O₄/γ-Fe₂O₃ was formed, in which the presence of ZnFe₂O₄ enhanced the thermal stability of γ-Fe₂O₃. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe₂O₃. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe₂O₃ content.     

BiVO4/BiPO4复合物的制备及可见光催化性能

采用水热法合成出具有不同V、P物质的量之比的BiVO₄/BiPO₄复合物.n_V/n_P分别为:0.1/9.9、0.5/9.5、1/9、3/7、5/5.采用 XRD、FE-SEM、EDS、拉曼、可见光光度计、漫反射以及电化学等测试手段对BiVO₄/BiPO₄复合物进行表征.在可见光条件下降解亚甲基蓝来评价BiVO₄/BiPO₄复合物的光催化活性.结果显示,当n_V/n_P<3/7的时候,BiVO₄/BiPO₄复合物的光催化活性随着BiVO₄含量的增加而增加,当n_V/n_P=3/7的时候,复合物具有最佳的光催化性能,反应速率常数k为0.005 1 min^-1,是纯BiPO₄的23.2倍.BiVO₄/BiPO₄复合物的光催化机制主要是由于BiVO₄的加入,提高了电子-空穴的分离率,进而提高了光催化活性.     

Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。     

A Structural Investigation of La2(GeO4)O and Alkaline-Earth-Doped La9.33(GeO4)6O2

The structures of the oxyorthogermanate La₂(GeO₄)O and the apatite-structured La_9.33(GeO₄)₆O₂ have been refined from powder neutron diffraction data. La₂(GeO₄)O crystallizes in a monoclinic unit cell (P2₁/c) and is cation stoichiometric in contrast to previous reports. La_9.33(GeO₄)₆O₂ crystallizes in a hexagonal unit cell (P6₃/m) and the powder diffraction data show anisotropic peak broadening that is observed in electron diffraction patterns as incommensurate diffuse spots at hkq reciprocal planes (with q=1.6-1.7) and can be attributed to a correlated disorder in the “apatite channels”. This compound was doped up to a nominal composition close to M₂La₈(GeO₄)₆O₂ with M=Ca, Sr, Ba. The dopant ions preferentially occupy the 4f sites as the number of La vacancies decreases. The measured ionic conductivity of La_9.33(GeO₄)₆O₂ is about 3 orders of magnitude larger than for La₂(GeO₄)O at high temperatures and decreases with increasing dopant content from the highest value of about 0.16 S cm⁻¹ at 1160 K.     

Alkylation of toluene with 1,3-pentadiene catalyzed by [bupy]BF4-AlCl3 and [bupy]BF4-FeCl3 ionic liquids

A new application of ionic liquids is developed for a novel process of synthesizing pentyltoluene from toluene and a C5 diolefin (1,3-pentadiene). The catalyst [bupy]BF₄-AlCl₃ behaves better than [bupy]BF₄-FeCl₃.     

Conjugate addition of indoles to α,β-unsaturated ketones using Cu(OTf)2 immobilized in ionic liquids

Indoles undergo smooth conjugate addition with α,β-unsaturated ketones in the presence of 10 mol% copper(II) triflate immobilized in air and moisture stable [bmim]BF₄ ionic liquid under mild conditions to afford the corresponding conjugate addition products in high to quantitative yields. The recovery of Cu(OTf)₂ is facilitated by the ionic liquid. The recovered catalyst was reused four to five times with consistent activity.