载气气氛对Co/MgMoO4催化剂CVD法高效合成碳纳米材料的影响

High yield and quality mutli-walled carbon nanotube (MWNT) bundles and carbon nanofibers were synthesized by catalytic decomposition of methane over Co/MgMoO₄ catalyst at 1 000 ℃. TEM studies showed that the products were mainly carbon nanofibers without carrier gas and were all MWNT bundles with hydrogen or nitrogen as carrier gas. Thermal gravimetric analyses (TGA) on the raw product indicated that the purity of MWNT was higher than 95wt%. The growth mechanism of carbon nanofibers and MWNTs was also discussed.     

BaWO4纳米线束的合成及其光学性质研究

High quality BaWO₄ nanowire bundles have been synthesized in toluene-sodium dodecylbenzene sulphonate (SDBS)-small amount PEG20000-H₂O reverse micelle system. XRD result shows that the obtained BaWO₄ belongs to tetragonal phase with scheelite structure. TEM results demonstrate that the obtained BaWO₄ nanowire bundles have high aspect-ratio (>650). The experimental results confirm that PEG20000 plays a key role for the formation of BaWO₄ nanowire bundles. Other factors which influence the morphology and crystallinity of the product are also briefly discussed. Moreover， the obtained BaWO₄ nanowire bundles exhibit strong photoluminescence centered at 397.3 nm with λ_ex=343.5 nm at room temperature， which is different from the bulk BaWO₄ crystals.     

电镀烧结法制备Ti/SnO2-Sb2O4电极的研究

The Ti/SnO₂-Sb₂O₄ electrode has been prepared by the electroplate-sinter method. The effect of SbCl₃ adding amount and sintering temperature on its electrode lifetime and oxygen evolution potential were investigated by means of EDX, SEM and XRD analysis. The results indicated that the electrode appeared the best performance when the SbCl₃ adding amounts was 0.2g and the sintering temperature was 550℃. In optimized conditions Ti substrate was entirely covered by SnO₂-Sb₂O₄ and the combinations among them were tight. Due to the use of electroplate method, the electrical conductivity, the oxygen evolution potential and the electrode lifetime were increased, so the elec-tro-catalytic activity and the electrochemical stability of the prepared electrode were found to be superior.     

纳米SrTiO3对高铁酸盐电化学性能影响研究

Two ferrates, K₂FeO₄ and BaFeO₄, had been prepared and characterized by XRD, IR and SEM. The electrochemical tests of the samples were carried out in the voltage range of 0.8～2.0 V and current density of 0.5～3.0 mA·cm^-2. The results indicated that performance of Zn-BaFeO₄ battery was superior to that of Zn-MnO₂ and Zn-K₂FeO₄ batteries. Nanometer SrTiO₃ prepared by Sol-gel methode with different ratio was added to the BaFeO₄ cathode in order to improve the discharge performance. The discharge capacity of the BaFeO₄ cathode was increased from 224 mAh·g^-1 to 246 mAh·g^-1 by addition of 5% nanometer SrTiO₃. The reason of enhancing BaFeO₄ electrochemical performance was discussed.     

四元体系CdCl2-LaCl3-(9.7%)HCl-H2O在298K的相平衡及其固相化合物的研究

The equilibrium solubility of the LaCl₃-CdCl₂-(9.7%)HCl-H₂O quaternary system at 298K was determined and the phase diagram was constructed. The results show that the system is complicated with four equilibrium solid- phases CdCl₂·H₂O， 8CdCl₂·LaCl₃·16H₂O(8∶1 type)， 4CdCl₂·LaCl₃·12H₂O(4∶1 type) and LaCl₃·7H₂O， respectively. The two new compounds 8CdCl₂·LaCl₃·16H₂O(8∶1 type) and 4CdCl₂·LaCl₃·12H₂O(4∶1 type) are congruently soluble in ～9.7% HCl-H₂O medium and have not yet been reported in literatures. Both com-pounds have been prepared from the system and have been characterized by XRD， TG-DTG and DSC.     

Sr2CeO4蓝色荧光粉体材料的柠檬酸盐分解法合成与表征

Pure Sr₂CeO₄ nanosized phosphors has been successfully synthesized via a citrate decomposition method at a temperature as low as 900 ℃. The particle sizes were estimated to be 80～120 nm by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The particle sizes were determined at the temperature of pre-decomposition, and would increase with the annealed temperature. Meanwhile, the photoluminescence properties of nano-Sr₂CeO₄ were investigated.     

离子层气相反应法(ILGAR)制备CuInS2薄膜的研究

CuInS₂ thin films have been prepared by ion layer gas reaction (ILGAR) using C₂H₅OH as solvent, CuCl and InCl₃ as reagents and H₂S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS₂ film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS₂ thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS₂ thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS₂ thin films is larger than 10⁴ cm^-1, and the band gap E_g is in the range of 1.30～1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10¹⁶ cm^-3.     

LiMn2O4的湿法合成及锰的光度法测定研究

The LiMn₂O₄ spinel was prepared by wet method using Li₂CO₃， Mn(CH₃COO)₂·4H₂O and CO₂ as raw ma-terials. The products were measured by TG/DTA， XRD， IR. The results Showed that the sample calcined at 800℃ for 10h was well crystallized monophase product. The contents of Mn(Ⅲ) and Mn(Ⅳ) of LiMn₂O₄ spinel were determined simultaneously by spectrophotometric analysis with pyrophosphoric acid.     

[Zn(en)3]SO4配合物大尺寸单晶的水热法生长和表征

Large size single crystals of [Zn(en)₃]SO₄ have been successfully grown by a hydrothermal process at 160℃ for 24h， using CuSO₄·5H₂O， ethylene diamine and reductive Zn powder as reactants. The diameters of the single crystals are range from 0.5mm to 1mm， and lengths reach up to 20mm. The single crystals were characterized by XRD analysis， FTIR and UV-Vis spectrum absorption measurements. The single crystal was confirmed to be [Zn(en)₃]SO₄ by performing powder diffraction of the single crystal. X-ray diffraction of the single crystals shows (100)-face to be cleavage face. The diffraction peaks are sharp and rocking curve for 200 diffraction has a narrow FWHM (the full width at half maximum)， which indicate the single crystal of [Zn(en)₃]SO₄ is perfect with less lattice distortion and defects. The single crystal appears transparent，and has constant weak absorption in UV-Vis spectrum region，which could be used as a novel optical crystal material.     

CrOx/ SBA-15介孔催化剂上丙烷在二氧化碳气氛中脱氢反应的研究

The structure and catalytic properties based on Chromium Oxide supported on mesoporous SBA-15 for oxidative dehydrogenation of propane by CO₂ have been studied by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and propane pulsing experiments in the absence of gas-phase O₂. It has been shown that propane conversion and propene yield increase with Cr loadings. The propane conversion and propene yield on CrO_x(Cr: 10wt%)/SBA-15 catalyst for oxidative dehydrogenation of propane by CO₂ at 550 ℃ reach 24.8% and 21.8%, respectively .The results of ESR, UV-Vis DRS and propane pulsing experiments indicate that Cr^Ⅲ in the CrO_x/ SBA-15 catalyst is the main active species in oxidative dehydrogenation of propane by CO₂ and Cr^Ⅵ, Cr^Ⅴ is inactive in dehydrogenation.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.