Regioselectivity nitration of aromatics with N2O5 in PEG-based dicationic ionic liquid

Regioselective mononitration of simple aromatic compounds has been investigated with N₂O₅ as nitrating agent and a new PEG200-based dicationic acidic ionic liquid (PEG₂₀₀-DAIL) as catalyst. The results of experiments show that this nitration system can significantly improve the para-selectivity of alkyl-benzenes and the ortho-selectivity of halogenated-benzenes. The PEG₂₀₀-DAIL exhibits recyclable temperature-dependant phase behavior in CCl₄ solvent, and it can be recycled without apparent loss of catalytic activity, and only 5% loss of weight is observed after six times recycling.     

Simultaneous determination of sugars and ascorbic acid by capillary zone electrophoresis with amperometric detection at a carbon paste electrode modified with polyethylene glycol and Cu(2)O

In this paper, a kind of novel carbon paste electrode modified with double modifiers-polyethylene glycol (PEG) and Cu(2)O (PEG/Cu(2)O CPME) in capillary zone electrophoresis with amperometric detection (CZE-AD) was applied to simultaneously determine three sugars: glucose, sucrose, fructose and ascorbic acid (AA). The catalytic electrochemical properties of PEG/Cu(2)O CPME could enhance sensitivity obviously compared with carbon paste electrode modified with only PEG or Cu(2)O at a relatively lower detection potential (+0.3 V versus SCE). Especially, the electrochemical detection response of AA increased obviously to the same level of saccharides by adding PEG into the Cu(2)O carbon paste modified electrode. The four analytes could be perfectly separated within 22 min, the linear ranges were from 1.0 x 10 (-6) to 5.0 x 10(-5) mol L(-1) and the detection limits were at 10(-7) mol L(-1) magnitude (S/N=3). The present working electrode was successfully employed to analyse beverage samples with recoveries in the range 93-107% and RSDs less than 4%. Above results demonstrated that capillary zone electrophoresis coupled with the PEG/Cu(2)O carbon paste modified electrode was of convenient preparation, high sensitivity, good repeatability and could be used in the rapid determination of practical samples.     

PEG1000-DIL/甲苯温控两相体系中硝基芳烃的还原反应

研究了PEG1000-DIL/甲苯温控体系中硝基芳烃的还原反应.考察了催化加氢、水合肼/FeCl3.6H2O和水合肼/Fe5HO8.4H2O等3种还原体系,发现水合肼/Fe5HO8.4H2O在PEG1000-DIL/甲苯温控体系中具有很高的催化活性,将其用于12种硝基芳烃的还原反应,产率最高可达99%.该催化体系重复使用3次后产率无明显变化,用于卤代硝基苯类化合物的还原可以有效防止脱卤副反应的发生.     

Compatibility study of 1,3,3-trinitroazetidinewith some energetic components and inert materials

The compatibility of 1,3,3-trinitroazetidine (TNAZ) with some energetic components and inert materials of solid propellants was studied by using the pressure DSC method. Where, cyclotetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine (RDX), nitrocellulose (NC), nitroglycerine (NG), 1.25/1-NC/NG mixture, lead 3-nitro-1,2,4-triazol-5-onate (NTO-Pb), aluminum powder (Al powder) and N-nitrodihydroxyethylaminedinitrate (DINA) were used as energetic components and hydroxyl terminated polybutadiene (HTPB), carboxyl terminated polybutadiene (CTPB), polyethylene glycol (PEG), polyoxytetramethylene- co-oxyethylene (PET), addition product of hexamethylene diisocyanate and water (N-100), 2-nitrodianiline (2-NDPA), 1,3-dimethyl-1,3-diphenyl urea (C₂), carbon black (C.B.), aluminum oxide (Al₂O₃), cupric 2,4-dihydroxybenzoate (β-Cu), cupric adipate (AD-Cu) and lead phthalate (φ-Pb) were used as inert materials. The results showed that the binary systems of TNAZ with HMX, NC, NG, NC+NG and DINA are compatible, with RDX and Al powder are slightly sensitive, with NTO-Pb, β-Cu, AD-Cu, C.B. and Al2O3 are sensitive, and with HTPB, CTPB, PEG, PET, N-100, 2-NDPA, C₂ and φ-Pb are incompatible.     

五氧化二钽纳米柱的水热合成和光催化性能

以聚乙烯醇(PEG)为结构导向剂,利用水热法合成了形貌可控的Ta2O5纳米柱.采用X射线衍射、扫描电镜、透射电镜、漫反射紫外-可见光谱和光致发光光谱对所制备样品进行了表征.考察了结晶时间和Ta2O5/Sr(OH)2摩尔比等合成参数对样品形貌的影响,并在此基础上对Ta2O5纳米粒可能的生长机理进行了推测.结果表明,在PEG和Sr(OH)2存在条件下可以合成形貌可控的Ta2O5纳米柱.研究了紫外光下Ta2O5纳米柱降解罗丹明B的光催化性能,发现Ta2O5的形貌对光催化性能有很大影响, Ta2O5纳米柱的光催化性能与其长度和直径比成线性关系.催化降解反应的表观速率常数最高可达0.156 min–1,且经多次循环使用后,样品仍然保持较高的催化性能.     

高能混合物的感度理论判别—— 不同配比和不同温度AP/HMX的MD研究

为了寻求高能复合材料的感度理论判据, 对高氯酸铵(AP)和HMX(环四甲撑四硝胺)所构成的不同质量比的二元混合体系, 用分子动力学(MD)方法和修正的PCFF力场, 作正则系综(NVT)下的周期性模拟计算, 求得其结合能和HMX热解引发键(N—NO2)的平均键长和最大键长. 结果表明, 结合能随质量比不同呈复杂变化趋势; HMX(N—NO2)引发键的最大键长随体系中HMX配比增加先增后减, 而当AP/HMX为1∶1时其值最大, 恰与此配比下感度最大的实验事实相一致. 选择质量比为1∶1的AP/HMX作不同温度下的NVT-MD模拟, 发现引发键(N—NO2)最大键长随温度升高而递增, 与感度随温度升高而增大的实验事实相符. 为此我们建议, 把高能复合材料中易爆燃组分引发键的最大键长作为其热和撞击等感度的理论判据, 借以阐明、比较或预示它们的相对安全性.     

染料敏化太阳能电池用琼脂糖基磁性聚合物电解质的电化学性能

以琼脂糖为聚合物基质,N-甲基吡咯烷酮为溶剂,磁性纳米粒子四氧化三铁为无机纳米颗粒添加剂制备了用于染料敏化太阳能电池(DSSC)的磁性聚合物电解质.通过研究不同小分子表面活性剂,聚乙二醇(PEG200)、曲拉通(TritonX-100)、乙酰丙酮和三者混合的表面活性剂对掺杂有1%(w)Fe3O4的磁性聚合物电解质离子电导率的影响,发现PEG200的加入可有效提高琼脂糖基磁性聚合物电解质的离子电导率.同时,对不同PEG200浓度添加下的电解质进行离子电导率测试研究发现:当PEG200加入量为61.8%(w)时,电解质具有最佳的离子电导率(2.88×10-3S·cm-1);对染料敏化太阳能电池进行电化学交流阻抗谱(EIS)测试的结果表明:染料敏化太阳能电池的电子寿命和复合电阻随着PEG200浓度的增加是先增大后减小,最大的电子寿命和复合电阻出现在PEG200浓度为68.3%(w)处.     

Adsorption and decomposition of HMX and CL‐20 on Al(111) surface by DFT investigation

The adsorption and decomposition of HMX and CL‐20 molecules on the Al(111) surface were investigated by the generalized gradient approximation of density functional theory. The calculations employed a supercell (6 × 6 × 3) slab model and three‐dimensional periodic boundary conditions. The strong attractive forces between HMX (or CL‐20) molecule and Al atoms induce the breaking of N‐O and N‐N bonds in nitro group. Subsequently, the dissociated oxygen atoms, NO₂ groups, and radical fragments of HMX or CL‐20 oxidize the Al surface. The largest adsorption energy is ?1792.7 kJ/mol in B1, where CL‐20 decomposes into four O atoms and a CL‐20 fragment. With the number of the radical species in adsorption configurations increases, the corresponding adsorption energy increases greatly. We also investigated the decomposition mechanism of HMX and CL‐20 molecules on the Al(111) surface. The activation energies (E _a) for the dissociations A2, A3, B1, and B6 are 31.2, 47.9, 75.5, and 75.9 kJ/mol, respectively. Although CL‐20 is more sensitive than HMX in its gaseous state, the E _a of CL‐20 is higher than that of HMX when they adsorb and decompose on the Al(111) surface, which indicates that the HMX is even easier to decompose on Al(111) surface as compared with CL‐20. Copyright © 2016 John Wiley & Sons, Ltd.     

黑索今的新型合成路线

以乙腈/三聚甲醛为原料合成1,3,5-三乙酰基-均-三嗪（TRAT）,再硝解制备黑索今(RDX)。 聚合反应中,当n(CH3CN)∶n(C3H6O3)=2∶1,n(H2SO4)∶n(C3H6O3)=1∶7.5,反应温度75 ℃,反应3 h时,TRAT的产率为95.2%。 硝解反应中,当n(N2O5)∶n(TRAT)=7∶1,n(HNO3)∶n(N2O5)=6∶1,反应温度45 ℃,反应1 h时,RDX的产率为87.2%。 RDX的全程产率为83.0%。 该工艺简单、易于控制,废酸污染小,有望应用于工业化生产。     

模拟燃烧热分解气体产物的在线分析-GAP/HMX混合体系压力下的快速热裂解

用T - Jump/FTIR在线联用分析技术,研究了GAP/HMX混合体系在模拟燃烧条件下快速加热高温高压的热裂解.结果表明,与GAP和HMX的单组分比较,GAP/HMX混合体系主要气体产物HCN的浓度明显提高,温度对主要气体产物浓度比HCN/NH3和N2O/HCN的影响与对单组分趋势一致,即随温度的提高HCN/NH、...     

固体填料对聚乙二醇结晶性的影响

采用DSC、WAXD技术研究了固体填料 (Al粉、奥克托金 (HMX)、高氯酸铵 (AP) )对聚乙二醇结晶性的影响 .Al粉及HMX不影响混合物中PEG的结晶度及晶体结构 ,高氯酸铵与PEG之间存在较强的相互作用 ,降低了混合物中PEG的结晶度 .某些金属盐也与PEG之间存在类似的相互作用 ,这种相互作用以金属盐溶于PEG熔体为前提 .高氯酸铵及金属盐导致PEG结晶度的降低是由于其阳离子与PEG分子链中的氧原子形成了络合物 ,增强了二者之间的相互作用 .     

H3PW12O40/CNTs吸附-分解NOx及微波作用效果

将碳纳米管(CNTs)载体分别经混酸与硝酸蒸气预处理并在不同温度下煅烧, 然后分别采用浸渍法及机械研磨法负载磷钨酸(HPW), 制备出HPW/CNTs催化剂, 对比考察了上述催化剂对NOx的吸附与分解效果. 在空速为10000 h-1、 吸附温度为200℃的条件下, 用0.5 g催化剂对1696 mg/m3的NOx进行吸附实验, 结果表明, 以硝酸蒸气预处理且经300℃煅烧后的CNTs为载体, 采用机械研磨负载法制备的催化剂HPW/CNTs对NOx的吸附率与吸附能力最高, 分别为54%与16.6 mg NOx/(g\5h). 对吸附NOx后的催化剂体系进行了催化分解NOx的程序升温脱附-质谱(TPD-MS)研究, 结果表明, 所吸附的NOx在快速升温过程中发生分解, 在此过程中有氧产生, 分解产物包括N2, O2及N2O. 采用电阻炉快速加热与微波辐射2种方式分别对吸附的NOx进行催化分解, 结果表明, 微波功率为700 W时, NOx分解为N2的收率为33.3%, 高于电阻炉以150℃/min快速升温的N2收率. 使用过的催化剂通水蒸气后可实现再生, 对再生后的催化剂进行循环使用研究, 结果表明, 再生后的催化剂吸附与催化分解NOx的性能未有明显下降.     

Investigation of swelling and network parameters of poly(ethylene glycol)-crosslinked poly(methyl vinyl ether-co-maleic acid) hydrogels

The influence of poly(ethylene glycol) (PEG) plasticiser content and molecular weight on the physicochemical properties of films cast from aqueous blends of poly(methyl vinyl ether-co-maleic acid) was investigated using thermal analysis, swelling studies, scanning electron microscopy (SEM) and attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy. FTIR spectroscopy revealed a shift of the CO peak from 1708 to 1731 cm⁻¹, indicating that an esterification reaction had occurred upon heating, thus producing crosslinked films. Higher molecular weight PEGs (10,000 and 1000 Da, respectively), having greater chain length, producing hydrogel networks with lower crosslink densities and higher average molecular weight between two consecutive crosslinks. Accordingly, such materials exhibited higher swelling rates. Hydrogels crosslinked with a low molecular weight PEG (PEG 200) showed rigid networks with high crosslink densities and, therefore, lower swelling rates. Polymer:plasticizer ratio alteration did not yield any discernable patterns, regardless of the method of analysis. The polymer-water interaction parameter (χ) increased with increases in the crosslink density. SEM studies showed that porosity of the crosslinked films increased with increasing PEG MW, confirming what had been observed with swelling studies and thermal analysis, that the crosslink density must be decreased as the M_w of the crosslinker is increased. Hydrogels containing PMVE/MA/PEG 10,000 could be used for rapid delivery of drug, due to their low crosslink density. Moderately crosslinked PMVE/MA/PEG 1000 hydrogels or highly crosslinked PMVE/MA/PEG 200 systems could then be used in controlling the drug delivery rates. We are currently evaluating these systems, both alone and in combination, for use in sustained release drug delivery devices.     

Oxidation of alkylarenes by nitrate catalyzed by polyoxophosphomolybdates: synthetic applications and mechanistic insights

Alkylarenes were catalytically and selectively oxidized to the corresponding benzylic acetates and carbonyl products by nitrate salts in acetic acid in the presence of Keggin type molybdenum-based heteropolyacids, H(3+)(x)()PV(x)()Mo(12)(-)(x)()O(40) (x = 0-2). H(5)PV(2)Mo(10)O(40) was especially effective. For methylarenes there was no over-oxidation to the carboxylic acid contrary to what was observed for nitric acid as oxidant. The conversion to the aldehyde/ketone could be increased by the addition of water to the reaction mixture. As evidenced by IR and (15)N NMR spectroscopy, initially the nitrate salt reacted with H(5)PV(2)Mo(10)O(40) to yield a N(V)O(2)(+)[H(4)PV(2)Mo(10)O(40)] intermediate. In an electron-transfer reaction, the proposed N(V)O(2)(+)[H(4)PV(2)Mo(10)O(40)] complex reacts with the alkylarene substrate to yield a radical-cation-based donor-acceptor intermediate, N(IV)O(2)[H(4)PV(2)Mo(10)O(40)]-ArCH(2)R(+)(*). Concurrent proton transfer yields an alkylarene radical, ArCHR(*), and NO(2). Alternatively, it is possible that the N(V)O(2)(+)[H(4)PV(2)Mo(10)O(40)] complex abstracts a hydrogen atom from alkylarene substrate to directly yield ArCHR(*) and NO(2). The electron transfer-proton transfer and hydrogen abstraction scenarios are supported by the correlation of the reaction rate with the ionization potential and the bond dissociation energy at the benzylic positions of the alkylarene, respectively, the high kinetic isotope effect determined for substrates deuterated at the benzylic position, and the reaction order in the catalyst. Product selectivity in the oxidation of phenylcyclopropane tends to support the electron transfer-proton transfer pathway. The ArCHR(*) and NO(2) radical species undergo heterocoupling to yield a benzylic nitrite, which undergoes hydrolysis or acetolysis and subsequent reactions to yield benzylic acetates and corresponding aldehydes or ketones as final products.     

离子液体中β-葡萄糖苷酶生物催化合成红景天甙

比较了聚乙二醇修饰的β-葡萄糖苷酶在三种离子液体([bmim]PF6,[bmim]BF4,[bmim]Tf2N)及两种常用有机溶剂(1,4-二氧六环、正己烷)中的催化性能,确定了适宜的反应介质;考察了底物浓度、温度、体系含水量和反应时间等因素对β-葡萄糖苷酶催化合成红景天甙反应的影响.结果表明,在最佳反应介质[bmim...     

Detection of the cyclic nitramine explosives hexahydro-1,3,5-trinitro- 1,3,5-triazine (RDX) and octahydro- 1,3,5,7-tetranitro- 1,3,5,7-tetrazine (HMX) and their degradation products in soil environments

The cyclic nitramine explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX) were examined in field and microcosm soil samples to determine their patterns of degradation and environmental fates. A number of analytical techniques, including solid-phase microextraction with on-fiber derivatization, gas chromatography-mass spectrometry, gas chromatography with electron-capture detection, liquid chromatography-mass spectrometry, and micellar electrokinetic chromatography were required for the analyses. Two different classes of intermediates were detected, both of which lead ultimately to the formation of nitrous oxide (N2O) and carbon dioxide (CO2). The first class was identified as the nitroso derivatives formed by the sequential reduction of -NO2 functional groups. The second class of intermediates, which was favored at higher humidities and in the presence of anaerobic sludge amendments, consisted of ring cleavage products including bis-(hydroxymethyl)-nitramine and methylenedinitramine. Rye-grass (Lolium perenne) present in field samples was found to extract and accumulate HMX from soil without further degradation. In all cases (excepting the plant samples), the indigenous microbes or amended domestic anaerobic sludge consortia degraded the cyclic nitramine explosives eventually to produce N2O and CO2.     

果胶负载钯催化剂的制备及Suzuki反应催化性能

以柑橘皮果胶为载体,采用吸附法制备了果胶负载钯催化剂,并将其应用于四苯硼钠与溴代芳烃的交叉偶联反应中.该反应体系以聚乙二醇400(PEG 400)/H2O为反应溶剂,三乙胺为碱,在空气中于110℃反应15~60 min,四苯硼钠中4个苯基均可顺利参与反应,高产率地获得相应的目标化合物.该方法具有条件温和、反应时间短、收率高且催化剂可循环利用等优点.     

Solid phase microextraction-high performance liquid chromatographic determination of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in the presence of sodium dodecyl sulfate surfactant

A simple and sensitive method has been developed using preconcentration technique solid phase microextraction (SPME) and analytical technique HPLC-UV for the determination of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from the environmental samples. Aqueous solution of anionic surfactant SDS was used for the extraction of both nitramine high explosives, viz., HMX and RDX from soil samples which were subsequently sorbed on SPME fiber. The static desorption was carried out in the desorption chamber of the SPME-HPLC interface in the presence of mobile phase ACN/methanol/water (30:35:35) and the subsequent chromatographic analysis at a flow rate of 0.5 mL/min and detection at 230 nm. For this purpose, a C(18), 5 microm RP analytical column was used as a separation medium in this method. Several parameters relating to SPME, e.g., adsorption/desorption time, concentration of salt, stirring rate, etc., were optimized. The method was linear over the range of 20-400 ng/mL for HMX and RDX standards in the presence of surfactant in aqueous phase, respectively. The correlation coefficient (R(2)) for HMX and RDX are 0.9998 and 0.9982, respectively. With SPME, the detection limits (S/N = 3) in ng/mL are 0.05 and 0.1 for HMX and RDX, respectively in the presence of the SDS surfactant. The developed method has been applied successfully to the analysis of real environmental samples like bore well water, river water, and ground alluvial soil.     

Branched mesoporous Mn3O4 nanorods: facile synthesis and catalysis in the degradation of methylene blue

Branched MnOOH nanorods with diameters in the range of 50-150 nm and lengths of up to tens of micrometers were prepared by using potassium permanganate (KMnO(4)) and PEG 400 (PEG=polyethylene glycol) as starting materials through a simple hydrothermal process at 160 °C. After annealing at 300 °C under a N(2) atmosphere for 5 h, MnOOH nanorods became gradually dehydrated and transformed into mesoporous Mn(3)O(4) nanorods with a slight size-shrinking. The as-obtained mesoporous Mn(3)O(4) nanorods had an average surface area of 32.88 m(2) g(-1) and a mean pore size of 3.7 nm. Through tuning the experimental parameters, such as the annealing atmosphere and temperature, β-MnO(2), Mn(2)O(3), Mn(3)O(4), MnO, and Mn(5)O(8) were selectively produced. Among these structures, mesoporous Mn(3)O(4) nanorods were efficient for the catalytic degradation of methylene blue (MB) in the presence of H(2)O(2) at 80 °C.     

Physico-chemical measurements of CL-20 for environmental applications. Comparison with RDX and HMX

CL-20 is a polycyclic energetic nitramine, which may soon replace the monocyclic nitramines RDX and HMX, because of its superior explosive performance. Therefore, to predict its environmental fate, analytical and physico-chemical data must be made available. An HPLC technique was thus developed to measure CL-20 in soil samples based on the US Environmental Protection Agency method 8330. We found that the soil water content and aging (21 days) had no effect on the recoveries (>92%) of CL-20, provided that the extracts were kept acidic (pH 3). The aqueous solubility of CL-20 was poor (3.6 mg l(-1) at 25 degrees C) and increased with temperature to reach 18.5 mg l(-1) at 60 degrees C. The octanol-water partition coefficient of CL-20 (log KOW = 1.92) was higher than that of RDX (log KOW = 0.90) and HMX (log KOW = 0.16), indicating its higher affinity to organic matter. Finally, CL-20 was found to decompose in non-acidified water upon contact with glass containers to give NO2- (2 equiv.), N2O (2 equiv.), and HCOO- (2 equiv.). The experimental findings suggest that CL-20 should be less persistent in the environment than RDX and HMX.