对醇氧化的一些特殊氧化剂的探讨

在对醇氧化的问题,需要用一些特定的氧化剂。本文通过介绍氧化铬、二氧化锰、二甲亚砜、异丙醇铝(或异丁醇铝)和分析这些氧化剂对不同的醇氧化问题,发现对于羟基所处的部位不同的醇,需要用到上述不同的氧化剂,才能得到理想的终端产品。     

复分解法制备硝酸羟胺的工艺研究

该文讨论了反应物的料比、反应时间和反应温度对复分解法制备硝酸羟胺(HAN)反应的影响,研究了蒸馏温度和真空度对硝酸羟胺稀溶液浓缩过程的影响,给出了硝酸羟胺含量的定量分析方法。     

Preparative Electrosynthesis of Strong Oxidizers at Boron-Doped Diamond Electrode in Anhydrous HF

The use of the boron-doped diamond electrode as a sufficiently stable electrode for electrochemical measurements/synthesis in liquid anhydrous hydrogen fluoride medium is reported. Electrooxidation of silver(I) has been studied in this solvent by using classical transient electrochemical methods and impedance spectroscopy. It has been found that faradaic currents related to silver(I) oxidation and the fluorine evolution reaction are reasonably separated at the potential scale, which allows efficient electrosynthesis of Ag^IIF₂, a powerful oxidizer. Impedance spectroscopy measurements provide insight into complex mechanism of AgF₂ formation. The procedure for electrosynthesis is provided for the first time in both galvanostatic and potentiostatic condition.     

Improved Access to Organo‐Soluble Di‐ and Tetrafluoridochlorate(I)/(III) Salts

A facile one‐pot gram‐scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF₄] ([cat]=[NEt₃Me]⁺, [NEt₄]⁺) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceeds via the [ClF₂]^? anion which is structurally characterized for the first time. The potential application of [ClF₄]^? salts as fluorinating agents is evaluated by the reaction with diphenyl disulfide, Ph₂S₂, to pentafluorosulfanyl benzene, PhSF₅. The CN moieties in acetonitrile and [B(CN)₄]^? are transferred in CF₃ groups. Exposure of carbon monoxide, CO, leads to the formation of carbonyl fluoride, COF₂, and elemental gold is dissolved under the formation of tetrafluoridoaurate [AuF₄]^?.     

Inorganic oxidizer detection from propellants,pyrotechnics, and homemade explosive powders using gradient elution moving boundary electrophoresis

Advancement in rapid targeted chemical analysis of homemade and improvised explosive devices is critical for the identification of explosives-based hazards and threats. Gradient elution moving boundary electrophoresis (GEMBE), a robust electrokinetic separation technique, was employed for the separation and detection of common inorganic oxidizers from frequently encountered fuel-oxidizer mixtures. The GEMBE system incorporated sample and run buffer reservoirs, a short capillary (5 cm), an applied electric field, and a pressure-driven counterflow. GEMBE provided a separation format that allowed for continuous injection of sample, selectivity of analytes, and no sample cleanup or filtration prior to analysis. Nitrate, chlorate, and perchlorate oxidizers were successfully detected from low explosive propellants (e.g., black powders and black powder substitutes), pyrotechnics (e.g., flash powder), and tertiary explosive mixtures (e.g., ammonium nitrate- and potassium chlorate-based fuel-oxidizer mixtures). Separation of these mixtures exhibited detection without interference from a plethora of additional organic and inorganic fuels, enabled single particle analysis, and demonstrated semiquantitative capabilities. The bulk counterflow successfully excluded difficult components from fouling the capillary, yielding estimated limits of detection down to approximately 10 μmol/L. Finally, nitrate was separated and detected from postblast debris collected and directly analyzed from two nitrate-based charges.     

Crystal structure of 2-nitrimino-5-nitro-hexahydro-1,3,5-triazine

The crystal and molecular structure of 2-nitrimino-5-nitro-hexahydro-1,3,5-triazine (NNHT) was determined. The relationship between the structural features of NNHT and its properties that pertain to its suitability as a potential oxidizer candidate for gun propellants is discussed. The NNHT structural features are also compared with analogous structural features of nitroguanidine (NQ) (Bracuti, A. J. J. Chem. Crystallogr. 1999, 29, 671) the more highly energetic triazine derivative, 1,3,5-trinitro-hexahydro-1,3,5-triazine (RDX) (Choi, C. S. and Prince, E. Acta.Crystallogr. B 1972, 28, 2857).     

Development and characterization of high performance solid propellants containing nano-sized energetic ingredients

This paper addresses the development of a pair of layered solid propellants suitable for use in a fast-core gun-propellant charge application. A baseline propellant combination was formulated using RDX particles and thermoplastic-elastomer binder as the major ingredients and CL-20 and nitroguanadine as separate additives for high- and low-energy propellants. The propellant’s burning rate was characterized and insufficient burning-rate ratio between the fast and slow baseline propellants was found. Impetus obtained from the combustion of the combined baseline propellants was also found to be far from the demanded value of 1300 J/g. Several modifications were made by introducing nano-sized aluminum particles and ultra-fine boron particles as well as high-energy oxidizer HNF into the propellant formulation. It was found that the addition of nano-sized aluminum particles can enhance the propellant burning rate only when the propellant contains oxidizers with a positive oxygen balance. Without the presence of positive oxygen balance oxidizer, the exothermic reaction of aluminum and boron particles occurs at a large distance from the burning surface introducing an energy-sink effect. The results obtained from the combustion of the advanced propellants show that an average impetus of 1299 J/g, a flame temperature of 3380 K with a burn rate ratio around 3 between the fast- and the slow-burning layers can be achieved. These conditions are desired for fast-core layered propellant applications. The impact sensitivities of the baseline, intermediate and advanced propellants were measured. The results show that addition of HNF and nano-sized aluminum exhibited improved impact sensitivity at levels that can be considered acceptable for deployment.     

新型高能氧化剂的合成方法及性能研究

新型高能氧化剂在固体推进剂中占据较大比重,是提高固体推进剂能量水平的关键材料之一。本文以ADN、HNF、TNAZ及HNFX为例,着重对其合成路线、物理化学、爆轰性能及改性等方面的最新研究进展进行综述,并展望了其在固体推进剂中的发展方向与应用前景。     

Stabilization of Lewis Acidic AuF3 as an N‐Heterocyclic Carbene Complex: Preparation and Characterization of [AuF3(SIMes)]

Two different reaction routes are described to access the unprecedented trifluoridoorganogold(III) complex [AuF₃(SIMes)]. The compound bears the N‐heterocyclic carbene SIMes (1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) as a ligand for a molecular Lewis acidic AuF₃ unit and was characterized by NMR spectroscopy as well as X‐ray crystallography. Apart from the use of a [AuF₄]^? salt as precursor, the strong oxidizing compound AuF₃ can be employed neat as starting material. The reaction proceeded even in organic solvents in the presence of SIMes as the ligand precursor. Decomposition reactions with the solvent can, therefore, be prevented by using this strategy.     

Crystal structure of 4,5-dinitroimidazole (45DNI)

A single-crystal X-ray diffraction study verified that the target oxidizer molecule, 4,5-dinitroimidazole (45DNI), had been synthesized. Some structural features of 45DNI are discussed and compared with those of 1,4-dinitroimidazole and 2,4 dinitroimidazole. 45DNI crystallizes with two crystallographically unique molecules in the monoclinic space group P2₁/n (#14) with unit-cell parameters a = 11.5360(8) Å, b = 9.071(1) Å, c = 11.822(1) Å, = 107.640(6)°, Z = 8, and has a density of 1.781 g/cm³. The molecular packing consists of infinite one-dimensional chains of 45DNI molecules approximately oriented in the ac direction which are linked by two different hydrogen bonds, and . In the lateral directions the chains are held together by molecular forces.