InCl3·4H2O Promoted Green Preparation of Xanthenedione Derivatives in Ionic Liquids

Xanthenediones derivatives have attracted considerable interests in recent times because they constitute a structural unit in a number of natural products1 and have been used as versatile synthons due to the inherent reactivity of the inbuilt pyran ring2. The conventional syntheses of xanthenediones were acid or base catalyzed condensation of appropriate active methylene carbonyl compounds with aldehydes3. However, many of these procedures involved longer reaction times,low yields and side reactions of aldehydes. In recent years, room temperature ionic liquids (RTILs) have been used as novel green reaction media4. Considering that InCl3 is an efficient Lewis acid catalyst used in promoting many organic reactions, especially in several condensation processes, we herein wish to report a very simple and green method for the preparation of poly-hydrogenated xanthenediones through InCl3·4H2O promoted cascade reaction of aldehydes and 5,5-dimethyl-l,3-cyclohexanedione in ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The preparative process presented here is operationally simple, environmentally benign and has the advantage of enhanced atom utilization. Furthermore, the solvent and the catalyst used can be recovered easily and reused efficiently.     

Synthesis and Structures of Titanosiloxane Cage Compounds

Reaction of (triphenylmethyl)silanetriol (1) with cyclopentadienyltitanium trichloride (CpTiCl₃) in the presence of triethylamine as a HCl scavenger gave both compounds of a partial open-cage type {[Ph₃CSiO(OH)]₃(Ph₃CSiO_3/2)(CpTiO_3/2)₄} (2) and cube type (Ph₃CSiO_3/2CpTiO_3/2)₄ (3). The 1:1 reaction of 1 and CpTiCl₃ in toluene solvent at reflux temperature for 3 d afforded compounds 2 (22%) and 3 (36%). When 1 is reacted with a 1.5 fold excess of CpTiCl₃ under the same conditions, compound 3 was obtained in high yield (81%) along with 2 in trace quantities. Compounds 2 and 3 were fully characterized by the analyses of ¹H, ¹³C, ²⁹Si NMR, IR, and FAB MS data. The solid-state structure of 3 was determined by a single crystal X-ray diffraction study. Compound 3 had shown to have catalytic activity for the oxidation of alkenes such as 1-octene, cyclooctene, and norbornene with t-butyl hydrogen peroxide. The effect of solvent was observed in this epoxidation reaction. The order of reactivity were decreased as follows: CHCl₃ > hexane THF.     

Reaction of 4,4′-dimethyldiphenyl ether with phosphorus trichloride in the presence of anhydrous aluminum chloride

The reaction of 4,4-dimethyldiphenyl ether with phosphorus trichloride in the presence of anhydrous aluminum chloride was studied. This reaction affords 2,8-dimethyl-10H-10⁵-phenoxaphosphine 10-oxide as virtually the only product. In air, the latter in an alkaline solution is quantitatively transformed into 10-hydroxy-2,8-dimethyl-10H-10⁵-phenoxaphosphine 10-oxide.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2762–2765, December, 2004.     

Cationic polymerization of dienes VIII: Is the elimination of cross-linking by a bulky electron donor a general behavior in the presence of aluminium trichloride?

Previous works on the polymerization of 1,3-pentadiene initiated by aluminium trichloride in non polar solvent at room temperature in the presence of bulky electron donor (ED) as tri-p-tolylamine have highlighted a stabilization of the polymerizing actives centres by ED, which allowed a reduction of some side reactions and the formation of more precisely defined polypentadienes than ever by cationic polymerization in non polar medium. The aim of this research was to investigate the role of bulky EDs such as tri-p-tolylamine and similar compounds in polar medium in order to obtain if possible a complete control of the polymerization of isoprene and 1,3-pentadiene. The beneficial effect of tri-p-tolylamine was shown in the case of isoprene polymerization at room temperature, with an important reduction of the cross-linked fraction for long reaction times and strong reduction of termination reactions. At −30 °C in the presence of tri-p-tolylamine, polypentadienes more controlled than in non polar solvent could be obtained, with a nearly complete elimination of the cross-linked fraction, while keeping the microstructure approximately constant.     

BaTiO3 and PbTiO3 perovskite as catalysts for methane combustion

Unsupported and γ-Al₂O₃-supported Ba and Pb titanate catalysts were prepared, characterized and studied in the combustion of methane, as a test reaction for VOCs’ catalytic combustion. They present good catalytic activities, and after dispersion (5%) on γ-Al₂O₃ the specific activity of the supported perovskite phase increased 25 and 30 times, respectively, compared with the unsupported samples. PbTiO₃/γ-Al₂O₃ shows the best catalytic properties among the tested samples.     

霍林河褐煤热解甲烷生成反应类型及动力学的热重-质谱实验与量子化学计算

应用开放体系的热重-质谱联用技术(TG/MS)对未成熟的霍林河褐煤(镜质组最大反射率ROmax为0.33%)进行了热解模拟, 获得了甲烷的在线析出速率曲线. 曲线拟合结果表明, 甲烷生成速率曲线可以分解为5个峰, 结合化学动力学分析, 发现低温阶段甲烷的峰为吸附甲烷析出峰, 其余四个峰为热解甲烷的生成峰, 代表四类不同的化学反应. 将煤的结构特征及量子化学的理论计算相结合, 认为甲烷的生成包括4类反应, 类型1为与氧等杂原子相连的脂碳断裂; 类型2包含了两种反应, 一种是短链脂肪烃类官能团β位断裂, 另一种是所形成的长链脂肪烃类物质二次裂解; 类型3是与芳核直接相连的甲基热解脱落; 类型4为存在于煤结构中脂肪类物质的芳香化.     

高活性锆掺杂钴催化剂的制备及其催化甲烷燃烧性能研究

由水热法制备了掺杂锆摩尔百分比为0，10，20，30．40，50％的钴催化剂，该系列催化剂对甲烷的低温催化燃烧显示出高活性．其中，10％Zr掺杂的催化剂活性最好，可在370℃使甲烷转化率达100％．XRD分析表明，该法制得的催化剂中的活性四氧化三钴物种是由一种晶态的碳酸钴前体分解而成，Co3O4为粒径在20～40nm之问的纳米粒子．用热重分析(TG)研究了碳酸钴前体的热分解行为．     

甲烷氧化细菌催化二氧化碳生物合成甲醇的研究

甲烷氧化细菌中包含的甲烷单加氧酶(MMO)、甲醇脱氢酶(ADH)、甲醛脱氢酶(FaldDH)、甲酸脱氢酶(FateDH)经过一系列反应能够把甲烷深度氧化生成二氧化碳，并生成一定的能量物质．把二氧化碳还原为甲醇是一个需要能量的过程，目前还没有已知的有机体在温和条件下完成这一反应．研究发现，甲基弯菌Methylosi-nus trichosporium IMV 3011可以催化二氧化碳生物转化生成甲醇．在休眠的悬浮细胞中充人二氧化碳后，反应一段时间在反应液中检测到了甲醇．二氧化碳转化成甲醇是一个需要能量推动的反应，为了补充反应所消耗的能量．反应一段时间后需要用甲烷进行再生，以恢复细胞中的还原当量NADH．我们进行了反应再生的交替连续批式反应，甲醇积累量能够维持在一个比较稳定的水平．理论上，反应不会增加温室效应，这是一个有效的、环境友好的、可恢复的反应过程．     

Empirical line parameters of methane in the 1.63–1.48 μm transparency window by high sensitivity Cavity Ring Down Spectroscopy

The positions and intensities of methane in the 1.58 μm transparency window have been measured by high sensitivity Cavity Ring Down Spectroscopy at room temperature. The achieved sensitivity allowed measuring intensities as small as 3 × 10⁻²⁹ cm/molecule i.e. three orders of magnitude smaller than the intensity cut off of the HITRAN line list of methane. The complete list contains a total of 16,149 transitions between 6165 and 6750 cm⁻¹. Their intensity values vary over six orders of magnitude from 1.6 × 10⁻²⁹ to 2.5 × 10⁻²³ cm/molecule. Transitions due to CH₃D in “natural” abundance in our methane sample were identified using a new spectrum of CH₃D recorded separately with a Fourier Transform spectrometer. From simulations of the CH₃D and methane spectra at low resolution, the CH₃D isotopologue has be found to contribute by up to 30% of the absorption near 1.58 μm.     

Methane and carbon dioxide solubility in 1,2-propylene glycol at temperatures ranging from 303 to 423 K and pressures up to 12 MPa

This work reports solubility data of methane and carbon dioxide in 1,2-propylene glycol and the Henry's law constant of each solute in the studied solvent at saturation pressure. The measurements were performed at 303, 323, 373, 398 and 423.15 K and pressures up to 4.5 MPa for carbon dioxide solubility and pressures up to 12.1 MPa for methane solubility. The experiments were performed in an autoclave type phase equilibrium apparatus using the total pressure method (synthetic method). All investigated systems show an increase of gas-solubility with the increase of pressure. A decrease of carbon dioxide solubility with the increase of temperature and an increase of methane solubility with the increase of temperature was observed. From the variation of solubility with temperature, partial molar enthalpy and entropy change of the solute for each mixture were calculated.