Copper‐Catalyzed Highly Selective Semihydrogenation of Non‐Polar Carbon‐Carbon Multiple Bonds using a Silane and an Alcohol

A copper catalyst bearing a suitable Xantphos derivative or NHC ligand was found to be highly efficient for the selective semihydrogenation of non‐polar unsaturated compounds using a mixture of a silane and an alcohol as reducing agent. The catalytic system was useful for the selective semihydrogenation of internal alkynes to (Z)‐alkenes with suppression of overreduction to the corresponding alkanes. Furthermore, semihydrogenations of terminal alkyne, 1,2‐diene, 1,3‐diene, 1,3‐enyne and 1,3‐diyne systems were also achieved selectively.     

Rhodium‐Cobalt Bimetallic Nanoparticles: A Catalyst for Selective Hydrogenation of Unsaturated Carbon‐Carbon Bonds with Hydrous Hydrazine

Our studies on the effect of metal compositions on the catalytic activity of the rhodium‐based bimetallic nanocatalysts revealed that the nanoparticles with a 4:1 ratio of rhodium to cobalt, were more active than the rhodium monometallic nanoparticles in the selective hydrogenation of unsaturated carbon‐carbon bonds with hydrous hydrazine as a hydrogen source. The nanocatalysts effected this hydrogenation process in good‐to‐excellent yields with high functional group tolerance, and could be reused 10 times without the loss of catalytic activity. The catalyst characterization by X‐ray photoelectron spectroscopy, transmission electron microscopy and line‐scanning analysis suggested that the coexistence of metallic rhodium and cobalt plays an important role in the enhancement of catalytic activity.     

Energetic Characteristics of HMX‐Based Explosives Containing LiH

The high energy density compound octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) and the strong exothermic compound LiH represent an excellent principal explosive and an active fuel, respectively. Herein, the energetic characteristics of HMX‐based explosives are explored by adding LiH as fuel additive. The detonation parameters of HMX‐based explosives containing LiH were tested with free‐field explosion experiments and compared with those of traditional TNT, HMX, and aluminized explosives. The results show that the explosives exhibit higher energy and present preferable explosion effect when LiH is added as an explosive ingredient. The improvement of impulse is more than 32.8 % at 2 m. The shock wave peak overpressure increases by almost 40 % at a distance of 3 m from detonation center specially for the explosive containing both LiH and Al additives. Elemental H and Li are expected to release tremendous energy to effectively improve the explosives instant damage power, but the detonation duration is shorter than that of Al‐containing mixed explosives, which may limit the advantage over Al in the impulse. Li₂CO₃ powder is the solid product of HMX/LiH, which explains the LiH oxidation during the explosion. The exothermic processes in the formation are the reason for the increased energy of HMX/LiH explosives. These results can provide guidance to a potential energetic system formed by HMX and LiH.     

Carbon‐Carbon Double Bond versus Carbonyl Group Hydrogenation: Controlling the Intramolecular Selectivity with Polyaniline‐Supported Platinum Catalysts

The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI‐supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition‐precipitation of H₂PtCl₆ onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol‐method). The PANI‐supported platinum catalysts were applied in the selective hydrogenation of the α,β‐unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO₂), alumina (Al₂O₃), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO₂ on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the β‐PtO₂ form) which is able to efficiently hydrogenate the conjugated CC bond of citral (selectivity to citronellal=87%), whereas reduction of the CO group occurs with polyaniline‐supported platinum (selectivity to geraniol/nerol=78%) prepared via the sol‐method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated CC or CO group is not only particularly useful for the selective hydrogenation of α,β‐unsaturated aldehydes but also unveils the great potential of conducting polymer‐supported precious metals in the field of hitherto barely investigated chemical catalysis.     

Synthesis and Properties of Nitrogen‐Containing Conjugated Microporous Polymers

The nitrogen‐containing conjugated microporous polymers (NCMPs) are synthesized by palladium‐catalyzed Sonogashira–Hagihara crosscoupling condensation of 1,3,5‐triethynylbenzene and bis(4‐bromophenyl)amine. The resulting NCMP sample exhibits good chemical and thermal stability due to its rigid structure. The choice of reaction solvents has a major influence on the porosity of NCMPs. The high specific surface areas of 945 m² g^?1 and 593 m² g^?1 are obtained for NCMP‐I and NCMP‐III using toluene and 1,4‐dioxane as solvent. Taking advantage of the good porous characters and the chemistry of amine groups, the NCMP‐I and NCMP‐III show superior adsorption performance for CO₂ and metal ions. The adsorption capacity of NCMP‐I and NCMP‐III for Ni (II) is measured to be 384 mg g^?1 and 362 mg g^?1. Given these excellent metal ions uptake, ease of preparation, and good physiochemical stability, the as‐synthesized NCMP samples show great potential in CO₂ uptake and removal of metal ions.

     

Lipase/Acetamide‐Catalyzed Carbon‐Carbon Bond Formations: A Mechanistic View

A lipase B from Candida antarctica (CALB)/acetamide‐catalyzed Michael addition of less‐activated ketones and aromatic nitroolefins has been developed, which is particularly interesting because neither CALB nor acetamide can independently catalyze the reaction to any appreciable extent. This co‐catalyst system was applicable to the Michael additions of cyclic and acyclic ketones to a series of aromatic and heteroaromatic nitroolefins. Hydrogen bonds between acetamide and cyclohexanone were confirmed for the observed activation by experimental facts, and new mechanistic insights into CALB/acetamide co‐catalysis are presented.     

Thermal Degradation Behavior of Poly(propylene) with a Novel Silicon‐Containing Intumescent Flame Retardant

Summary: A novel intumescent flame retardant (PSiNII), containing silicon, phosphorus and nitrogen, has been synthesized and incorporated into poly(propylene) (PP). The flame retardancy of PP/PSiNII, evaluated by the limiting oxygen index (LOI) value, can be enhanced up to 29.5 vol.‐% from 17.4 vol.‐% with 20% total loading amount of PSiNII. The thermal degradation behavior of PP/PSiNII are investigated by thermogravimetric analysis (TGA) under nitrogen and air, and pressure differential scanning calorimetry (PDSC) under 1.5 MPa of oxygen. The PP/PSiNII‐3 degrades at 400 °C for different time, and the process is investigated by FTIR which indicates there is P? O in the char. The morphologies of char formed at 400 °C for 10 min and after LOI test are investigated by scanning electron microscopy (SEM). The morphological structure of the char exhibits the swollen cells in the inner and a smooth outer surface, which do good to the thermal properties and fire performance of PP. The thermal stability of PP is improved by incorporating PSiNII.

Inner surface of PP/PSiNII‐3 after LOI test.     

Desulfitative Carbon–Carbon Cross‐Coupling of Thioamide Fragments with Boronic Acids

A novel and general carbon–carbon cross‐coupling reaction between cyclic thioamides and boronic acids is described. The reaction is catalytic in palladium(0) and requires stoichiometric amounts of a copper(I ) carboxylate as metal cofactor. The mode of cross‐coupling in the reaction of cyclic thioamides with boronic acids is easily tunable between carbon–carbon and carbon–sulfur cross‐coupling. While the catalytic palladium(0)/copper(I ) system provides carbon–carbon bond formation with extrusion of sulfur, stoichiometric quantities of copper(II ) under air mediate carbon–sulfur bond formation.     

城市湖泊的臭氧降解研究

研究臭氧降解方法去除城市湖泊湖水中有机污染的可行性。以广州市五个湖泊湖水为原水样．分别用重铬酸钾法和微生物法BOD快速测定仪测定臭氧降解前后湖泊水的COD和BOD值,并探讨了降解时间的影响。结果表明．臭氧降解方法可以去除城市湖泊中部分有机物质,广州市五个湖泊中麓湖COD去除率最高达49．4％,其它湖泊COD去除率30．0％～35．0％．而且臭氧降解方法还可以提高湖水中有机物的可生化性。     

Near‐Infrared and Visible Absorption Spectroscopy of Nano‐Energetic Materials Containing Aluminum and Boron

Near‐infrared and visible absorption spectra are measured for nano‐energetic materials consisting of thirteen different types of Al or B nano‐particles in the 30 nm to 1 μm size range embedded in nitrocellulose or Teflon oxidizers, using an integrating sphere absorption spectrometer. The Al nano‐particle absorption is generally similar to the spectra of bulk Al, but the absorption strength is size‐dependent and up to twelve times more intense. Absorption coefficients are determined as a function of nano‐particle loading. For Al particles where the size is known, per particle cross sections are also determined. The ratio of cross section to volume decreases with increasing particle size. The implications of these measurements for nano‐sized energetic material analysis and for laser‐ignition experiments are briefly discussed.     

Sulfonic Acid‐Catalyzed Autoxidative Carbon‐Carbon Coupling Reaction under Elevated Partial Pressure of Oxygen

An aerobic organocatalytic oxidative C C bond formation reaction of benzylic C H bonds with various C‐nucleophiles is described. The coupling reaction proceeds by simply stirring the substrates under elevated partial pressure of oxygen in the presence of a sulfonic acid catalyst at room temperature. Elevation of the pressure enables the reaction of a broad scope of nucleophile substrates otherwise showing poor reactivity at ambient pressure. The benzylic C H bonds of xanthene, acridanes, isochromane and related heterocycles could be functionalized with nucleophiles including ketones, 1,3‐dicarbonyl compounds and aldehydes. Electron‐rich arenes could be utilized as nucleophiles at elevated temperatures. The reactions are believed to proceed via autoxidation of the benzylic C H bonds to the hydroperoxides and subsequent nucleophilic substitution catalyzed by sulfonic acids.     

Synthesis of Water-Soluble Polyesters Containing Carboxy-Functional Groups in the Polymers Chain and Study of Their Metal Complexes

The diethylenetriaminepentaacetic acid bisanhydride (DTPABA) was synthesized from diethylenetriaminepentaacetic acid (DTPA) and was further subjected to polyaddition with diols like polyethylene glycols (PEG) of different molar masses to form the polyesters. The polyesters synthesized were soluble in water as well as organic solvents and show better complexing ability than their monomer. The metal complexes of polyesters were synthesized by the reaction of water-soluble polyesters with copper acetate. The synthesized water-soluble polyester and their copper complexes were characterized by their melting points, elemental analysis, UV–Vis spectroscopy, viscometry, FTIR, ¹H NMR, SEM, AFM, XRD data, thermal stability of the compounds synthesized was studied by TG-DTA analysis. The antibacterial activity of synthesized polyesters has been studied against the bacterial species Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis.     

Iodine‐Catalyzed Intramolecular Oxidative Thiolation of Vinylic Carbon‐Hydrogen Bonds via Tandem Iodocyclization and Dehydroiodination: Construction of 2‐Methylene‐3‐thiophenones

A metal‐free vinylic carbon‐hydrogen bond thiolation has been developed. Under the catalysis of iodine (10 mol%), the cyclization of α‐alkenoyl ketene dithioacetals afforded a broad range of polyfunctionalized 2‐methylene‐3‐thiophenones in good selectivity with moderate to excellent yields via tandem iodocyclization and dehydroiodination. The synthetic strategy can also be extended to the cyclization of ortho‐methylthiophenyl vinyl ketones leading to 2‐methylene‐3‐benzothiophenones.

     

树脂负载催化剂臭氧催化降解甲基红废水

该文进行了制备的载亚铁阳离子交换树脂对甲基红染料废水的降解效果的研究。通过对比试验验证催化剂活性,进而考察了pH、臭氧投加量及催化剂投加量对甲基红降解效果的影响。结果表明,对于100mg／L的甲基红溶液,加入一定量催化剂,臭氧投加量为O．5g／h,pH为9的条件下,甲基红的色度去除率可达99．1％,COD去除率为69．5％。通过试验证明,该催化剂能有效催化降解甲基红废水。     

Synthesis and Reactions of Organometallic Polymers Containing Titanacyclobutene Units in the Main Chain

A new class of polymers containing titanacyclobutene units in the main chain were prepared by the reaction of organic dihalides (2) with a binuclear titanium propargyl complex (3) generated in situ from bis(pentamethylcyclopentadienyl)titanium chloride (Cp*₂TiCl, 1), SmI₂, and 1,4-bis(3-bromopropynyl)benzene (2a). The dark red colored polymers (4) thus obtained are soluble in organic solvents such as tetrahydrofuran and chloroform, and they are stable at ambient temperature under argon atmosphere. The reaction of the titanium-containing polymers (4) with hydrogen chloride was found to give organic polymers (7) containing unsaturated main chain.     

臭氧法处理电镀含镍废水工艺研究

本论文采用O₃+UV+Ca(OH)₂法处理含镍废水,对氢氧化钙加入量、臭氧流量、反应时间、pH和紫外灯功率等影响因素进行了分析,利用DesignExpert 8.0中Box-Behnken法进行了响应面设计,并对实验数据进行了优化。结果表明,最佳废水处理的工艺条件为:紫外灯功率30 W,氢氧化钙加入量59.5 mg,臭氧流量98.7 mL·min^-1,反应时间29.3 min,pH 7.9。在此条件下处理后的废水中镍离子浓度为0.0865 mg·L^-1,达到排放标准。     

DOPO‐Based Phosphorus‐Containing Methacrylic (Co)Polymers: Glass Transition Temperature Investigation

A two‐step synthetic procedure is designed for preparing new flame‐retardant methacrylic monomers containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a substituent side group. DOPO and methacrylate moieties are linked by linear aliphatic hydrocarbon spacers (3 to 11 carbon atoms). Copolymerization with methyl methacrylate is carried out leading to copolymers containing between 2 and 10 wt% phosphorus. All homo‐ and copolymers exhibit a unique glass transition temperature (T_g ). A new group contribution for DOPO‐based substituent is extracted that leads to reasonable estimations of T_g s of other published polymers. The Fox equation provides a good estimation of T_g s for most copolymers and for physical blends of poly(methyl methacrylate) (PMMA) and DOPO. When using monomers having three and four carbon atoms in the hydrocarbon spacer, the T_g of copolymers remains close to that of PMMA over a wide range of composition.     

Novel Melt‐Castable Energetic Pyrazole: A Pyrazolyl‐Furazan Framework Bearing Five Nitro Groups

Continuing advances in energetic pyrazole construction foster further its rational use. This work establishes an approach for the first synthesis of nitropyrazole that bear both furazan and trinitromethyl moieties. The approach to the installation of the C(NO₂)₃ group exploits the destructive nitration of N‐acetonyl group. The target 3‐(3,4‐dinitro‐1‐(trinitromethyl)‐1H‐pyrazol‐5‐yl)‐4‐methylfurazan ( 6 ) has promising explosive properties.