Thermal Decomposition Behavior and Non-isothermal Decom-position Reaction of Copper(II) Salt of 4-Hydroxy-3,5-dinitro- pyridine Oxide and Its Application in Solid Rocket Propellant

Introduction Copper(II) salt of 4-hydroxy-3,5-dinitropyridine ox-ide (4HDNPOCu) is an energetic material containing energetic groups of NO2, which can be used as an ener-getic auxiliary catalyst substituting the inertia copper salt to improve the catalysis of the main catalyst (lead salt) in Composite Modified Double Base propellant containing RDX (RDX-CMDB propellant).1 Thermal behavior is one of the most important aspects affecting its catalytic efficiency for propellant. However, …     

Thermal Behavior, Non-isothermal Decomposition Reaction Kinetics of Copper(Ⅱ) Salt of 4-Hydroxy-3,5-dinitropyridine and Its Application in Propellant

The thermal behavior and kinetic parameters of the major exothermic decomposition reaction of the title compound in a temperature-programmed mode were studied by means of TG-DTG and DSC. The critical temperature of thermal explosion was calculated. The effect of the title compound on the combustion characteristic of composition modifier double base propellant containing RDX was explored with a strand burner. The results show that the kinetic model function in differential forms, the apparent activation energy(Ea) and the pre-exponential factor(A) of the major exothermic decomposition reaction are 3(1-α)[-ln(1-α)]2/3, 190.56 kJ/mol and 1013.39 s-1, respectively. The critical temperature of thermal explosion of the compound is 353.08 ℃. The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as dα/dT=1014.65(1-α)[-ln(1-α)]2/3 e-2.2920×104/T. As an auxiliary catalyzer, the title compound can help the main catalyzer of lead salt of 4-hydroxy-3,5-dinitropyridine to accelerate the burning rate and reduce the pressure exponent of RDX-CMDB propellant.     

Kinetic Study on the Exothermic Decomposition Reaction of 2,4,6,8-Tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]onan-3,7-dione

Introduction 2,4,6,8-Tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]nonan- 3,7-dione (1) is a novel energetic cyclourea nitramine containing four —NO2 groups (Figure 1). The detona-tion velocity corresponding to =1.93 gcm-3 is 9034 ms-1. It is the potential high explosive. Its preparation,1 properties1 and hydrolytic behavior2 have been reported. Thermal behavior is one of the most important aspects of the compound in practical application. However, its kinetic parameters of thermal decomposition…     

A Study of Estimating the Safe Storage Life, Self-accelerating Decomposition Temperature and Critical Temperature of Thermal Explosion of Double-base Propellant Using Isothermal and Non-isothermal Decomposition Behaviours

The pressure exponent (γ) equation of the burning rate (u) of the title propellant is u=apγ=4.350p0.192 at 4-10 MPa, having very good combustion characteristics. It has the potential for possible use as solid rocket propellant from the point of view of …     

Photoluminescence quenching of quantum-confined cadmium sulfide clusters by norbornadiene derivatives

Influence of norbornadiene and its derivatives on the photoluminescence (PL) of quantum-confined cadmium sulfide clusters (Q-CdS) prepared in reverse micelles was investigated.It was found that norbornadiene-2,3-dicarboxylic acid (3) and its monopotassium salt (4) quenched PL intensity by 77% and 62%,respectively,whereas its dipotassium salt (5),norbornadiene (1) and norbornadiene-2,3-dimethylcarboxylate (2) had no effect on PL intensity.The formation constants for adducts formed between defect sites at the surface of Q-CdS clusters and 3 or 4 were also determined.PL quenching effect was attributed to the presence of ionizable proton which is considered to be able to trap photogenerated electrons and remove them from possible decay process.Measurements of the PL decay by single photon counting technique also supported these steady-state observations.     

In-situ synthesis of nanoparticles via supersolubilizing micelle self-assembly

In-situ synthesis of nano-particles using the self-assembly of molten salt and super soluble micellae was proposed based on a phenomenon of super solubilization of molten salt in reverse micellae and its self-assembly when the concentration reached up to 95%(w/w).The mechanism of the self-assembly indicates that the self-assembly of molten salt occurs in a reverse micelle where a homogenous phase is established between 5%(w/w)of a surfactant with a VB value of less than 1 and a hydrocarbon spe- cies.This synthesis has some unique features,such as being free of water,highly effective deposition and narrow distribution of particle size.     

Lewis Acid Modulation in a Amido-functional Diarylethene and Its Hypsochromism Effect

A photochromic diarylethene,1,2-bis(2-methyl-5-(4-N,N-dimethylaminophenyl)thien-3-yl)perfluorocyclopen-tene in proton-donating media was studied.The ammonium salt came into being in the presence of acetic acidfollowing localization of lone pair electrons of the amino group.The maximum absorption of the salt had a 36 nmhypsochromic shift,and its molar extinction coefficient increased to 3.494×10~4 L·mol~(-1)·cm~(-1).The conjugationaland delocalizational energy levels were calculated by Gaussian 98,and its hypsochromic shift mechanism was alsodiscussed.     

Synthesis and Catalytic Activity of Copper （Ⅱ） Resorcylic Acid Nanoparticles

IntroductionCopper(Ⅱ) resorcylic acid is a type of conven-tional burning rate catalyst commonly used in solid pro-pellant. Burning rate is considered as an important pa-rameter in the performance of solid propellant. Recentliterature has shown that the b…     

Heterogeneous reaction of NO_2 on the surface of NaCl particles

Sodium chloride is the major constituent of sea salt particles in atmospheric environment, with an esti- mated annual contribution of 1012 kg of sea salt parti- cles to the atmosphere[1]. Many studies have shown a significant chloride deficit in these particles when compared to bulk seawater[2,3]. This deficit has been attributed to reactions with NOx and SO2[4]. Simulta- neously, NO2 is one of the main pollutants of mobile vehicles. Reaction (1) may be particularly important to the atmosph…     

Electrospray Lonization Fourier Transform Ion Cyclotron Resonance Mass Spectrometric Study on Sodium Azide Cluster Ions

Sodium azide has rarely been studied in gas phase or in the form of cluster ions and as a model of solid energetic substances and inorganic azide salt was ionized by electrospray ionization (ESI) and studied by high resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) systematically. This paper highlights the effects of experimental conditions on the formation of salt cluster and the collision activation dissociation pathways of cluster ions to develop a microscopic understanding of inorganic azide salt clusters.     

Flow Injection Chemiluminescence Analysis of Low Level Concentration of Hydrazine

IntroductionHydrazine is often used as high-energy propellant in space shuttle program, and it is an important precursor in polymer industry, pesticides, and pharmaceuticals1,2. However, owing to its intensive mammalian toxicity, the monitoring of hydrazine residues in environment matrices has become a priority field in industrial laboratories. Siontorou et al.3,4 and Marrazza et al.5 recently designed a kind of DNA biosensor for monitoring pollutant including hydrazine. Some electrochemical…     

Thermal Decomposition Kinetics of Triethylene Glycol Dinitrate

Introduction Triethylene glycol dinitrate (TEGDN) is a novel en-ergetic material containing two groups of NO2, which can be used as an energetic plasticizer ingredient in propellants because of its excellent proformance.1 It exhibits lower impact sensitivity, better thermostability, weaker poisonousness and volatility, and stronger effec-tiveness of plasticizing cellulose nitrate than nitroglyc-erine (NG). As a new plasticizer TEGDN has good ap-plication prospects in the near future. The…     

A Mild and Efficient Procedure for the Preparation of Chromone-2-carboxylates

Chromone-2-carboxylates are widely used for the pharmacological activity of several of its derivatives1. The general synthesis of such chromone derivates includes two steps (Scheme 1): a Claison condensation of dialkyl oxalate with 2-hydroxyacetophenones to achieve alkyl 3-(2-hydroxyphenyl)-3-oxopropanoates in the presence of NaH, NaOEt, or NaOMe; cyclodehydration of the alkyl 3-(2-hydroxyaryl)-3-oxopropanoates to obtain chromones under acid condition. The total yield of the two steps is q…     

Synthesis and Crystal Structure of 2,5-Di- （pyridin-3-yl）-1,3,4-oxadiazolendium Nitrate

In order to continue our studies on the synthesis, properties and coordination of s-tetrazine, 3,6-di-(pyridin-3-yl)-s-tetrazine (II, 3-dptz) was synthesized and characterized by 1H- NMR, MS and IR spectra. And the coordination reaction of 3-dptz with nitrate of Cu(II) was studied. 3-dptz reacting with CuII salt [Cu(NO3)2·2H2O] generates a new salt, nitrate of 2,5-di-(pyridin-3- yl)-1,3,4-oxadiazolene (III). III was determined by IR spectra and single-crystal X-ray diffraction to give the following crystal data: space group P21/c, a = 4.9112(1), b = 8.4101(3), c = 29.499(1) , β = 93.266(2)o, V = 1216.44(7) nm3, Mr = 287.24, Z = 4, Dc = 1.568 g/cm3,μ= 0.122 mm-1, F(000) = 592, R = 0.0430 and wR = 0.1240. The results show that III is composed of one cation and one nitrate anion. The cation consists of one H+ and one 2,5-di-(pyridin-3-yl)-1,3,4-oxadiazol molecule, with the former being attached to the latter via electrovalent bond with N3 atom. And the O(42) atom in the nitrate anion is disordered. Intra- and intermolecular H-bonds are observed in the crystal of the title compound. The mechanism of metal-assisted decomposition was also discussed briefly.     

Density Functional Calculations of C–NO_2 Bond Dissociation Energies for Nitroalkanes Molecules

Bond dissociation energies for the removal of nitrogen dioxide group in some nit- roalkane energetic materials have been calculated by using the three hybrid density functional theory (DFT) methods B3LYP, B3PW91 and B3P86 with 6-31g** and 6-311g** basis sets. The computed BDEs have been compared with the available experimental results. It is found that the B3P86 method with 6-31g** and 6-311g** basis sets can obtain satisfactory bond dissociation energies (BDEs), which are in extraordinary agreement with the experimental data. Considering the smaller mean absolute deviation and maximum difference, the reliable B3P86/6-311g** method was recommended to compute the BDEs for the removal of nitrogen dioxide group in the nitroalkane energetic materials. Using the method, the BDEs of 8 other nitroalkane energetic materials have been calculated and the maximum difference from experimental value is 1.76 kcal·mol-1 (for the BDE of tC4H9–NO2), which further proves the reliability of B3P86/6-311g** method. In addition, it is noted that the BDEs of C–NO2 bond change slightly for main chain nitroalkane compounds with the maximum difference of only 3.43 kcal mol-1.     

The Purification and Rapid Identification of Heavy Metal-binding Peptides of Water Hyacinth

This paper studies the rapid identification of heavy metal-binding peptides (phytochelatin) by taking Water Hyacinth as a model plant. Plants were cultured in water containing 2 μg/ml Cd2+ for 13 days. The Sephadex G-50 chromatography of root extract under low salt concentration (0. 01 mol/L PBS) gave a Cd-binding peak with MW of 10 ,000 determined by SEC HPLC. After oxidation with performic acid, its SEC HPLC molecular weight decreased to below 1300 and the reverse phase HPLC showed one peptide peak, whose amino acid composition is the same as that of the sample never undertaking oxidation, and (Glu/Gln):Cys:Gly=2:2:1. According to the general structure of phytochelatin (γ-Glu-Cys)n-Gly, n is 2 in this case. The protocol including the sequential steps of Sephadex G-50 chromatography→performic acid oxidation→reverse phase HPLC→amino acid analysis is a rapid and effective method to identify the existence of phytochelatin and determine its values of n.     

Evaluation of Transient Absorption Spectra of N, N, N, N- Tetra - ( p -methylphenyl ) - 4, 4- diamino - 1, 1- diphenyl Ether ( TPDAE ) for Electron Transfer from TPDAE to Fullerenes ( C_(60) / C_(70) ) by Laser Flash Photolysis

Fullerenes C60 and C70 have high electron affinity ( 2.6 - 2.8 ev ) and readily form anions on electronchemical reduction1, which were famous as electron acceptor in photo-excitation because of symmetrical shape, large size, and properties of its p - electron system2. After observation of molecular ferromagnetism3 in the tetrakis (dimethylamino ) ethylene salt of C60 as well as the occurrence of ultra-fast photoinduced electron transfer within the dimethyl aniline - C60 complex4, prompted us…     

Study on the Phase Equilibrium of the Ternary System Ethanol-Cesium Carbonate-Water at 10, 30 and 50℃

Introduction The salting out effect in the systems of aliphatic al-cohol-water is of industrial interest. The addition of or-ganic solvents to the aqueous solution of a salt normally decreases the solubility of the salt. So the method can be used for salting-out of inorganic salts to improve yield and purity.1-3 However, the phase diagrams of the inves-tigated systems are required as basic data. There are lots of aliphatic alcohol-water systems having been deter-mined. The 1-butanol-water-Na…     

Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over HZSM-5 modified by NH4F and SrO

The methylation of 2-methylnaphthalene (2-MN) into 2,6-dimethylnaphthalene (2,6-DMN) was investigated over the solid acid catalysts.The results show that HZSM-5 modified by NH_4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity.When NH_4F/HZSM-5 is further modified by SrO,its catalytic activity decreases due to the decrease in the total acid amount and acidic strength.As a result,the comprehensive modification of NH_4F and SrO leads to the increase in the 2,6- DMN selectivity (2,6-DMN to DMN),up to 64.8% when 2-MN conversion is 10%.We calculated the ESP charge by density functional theory and the results show that the 6-position in 2-MN has higher ESP charge value than 7-position.The formation of 2,6-DMN is favored energetically as compared to that for 2,7-DMN.This suggests during the alkylation of 2-MN inside the ZSM-5 channel,the formation of 2,6-DMN is favored electronically than that of 2,7-DMN.Hence,lowering the acidity of catalyst is a key factor to obtain high selectivity of 2,6-DMN.     

Synthesis and light absorption of benzotellurazole crown ether cyanine dye

Various methods for synthesis of 2-methyl-5,6-(1,4,7,10,13-pentaoxatridecamethyl-ene)benzotellurazole (8) are described. Under different conditions, alkylation of compound 8 with methyl iodide gave telluronium salt 1,2-dimethyl-5,6-(1,4,7,10,13-pentaoxatridecamethylene)benzo-tellurazolium iodide (15) or quaternary ammonium salt 2,3-dimethyl-5,6-(1,4,7,10,13-pentaoxatri-decamethylene)benzotellurazolium iodide (14) in high yields, repectively. The cyanine dye 3,3'-dimethyl-5,6,5',6'-bis(1,4,7,10,13-pentaoxatridecamethylene)telluracarbocyanine iodide (16) is obtained by condensation of 14 with ethyl orthoformate in acetic anhydride. The visible absorption of the cyanine dye is also discussed.