Studies on Energetic Compounds Part 23: Preparation,Thermal and Explosive Characteristics of Transition Metal Salts of 5‐Nitro‐2,4‐Dihydro‐3H‐1,2,4‐Triazole‐3‐One (NTO)

Five transition metal salts of 5‐nitro‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐one, [namely M(NTO)_n⋅mH₂O where M is Ag, Hg, Cd, Cr, Fe where n=1,2,2,3,3 and m=1,2,2,8,2 respectively] were prepared and characterized (hereafter these compounds will be named as AgNTO, HgNTO, CdNTO, CrNTO and FeNTO, respectively). Their thermal decomposition was investigated by TG, DTA whereas explosive behaviour has been studied in terms of explosion delay, impact and friction sensitivities. Further, kinetic parameters have been derived using non‐isothermal TG data and mechanism of thermolysis has also been proposed. It seems that dehydration takes place prior to the evolution of NO₂ and the subsequent ring rupture yielding metal oxide. AgNTO on the other hand yields metallic silver. Dehydration in the case of HgNTO occurs in two steps: at each step one molecule is lost. All the salts are insensitive to impact and at the same time insensitive to friction up to 360 N.     

High Pressure Raman Spectroscopy of Nitric Acid / 2‐Nitropropane Mixtures

High pressure Raman spectroscopy measurements in a diamond anvil cell (0–20 GPa) on HNO₃‐2‐nitropropane mixtures are reported. These mixtures have been chosen as a model propellant, where neither component is explosive by itself. The high pressure decomposition of the mixture with oxygen balance (O.B.=0) has been observed and the recovered products analyzed and identified. The initiation of the chemical decomposition is correlated with he weakening of the N O bonds in the mixture. The study of a mixture at O.B.=0 with H¹⁵NO₃ permitted us to determine the origin of the nitrogen formation and to suggest a chemical pathway.     

Triazidotrinitro Benzene: 1,3,5‐(N3)3‐2,4,6‐(NO2)3C6

Triazidotrinitro benzene, 1,3,5‐(N₃)₃‐2,4,6‐(NO₂)₃C₆ ( 1 ) was synthesized by nitration of triazidodinitro benzene, 1,3,5‐(N₃)₃‐2,4‐(NO₂)₂C₆H with either a mixture of fuming nitric and concentrated sulfuric acid (HNO₃/H₂SO₄) or with N₂O₅. Crystals were obtained by the slow evaporation of an acetone/acetic acid mixture at room temperature over a period of 2 weeks and characterized by single crystal X‐ray diffraction: monoclinic, P 2₁/c (no. 14), a=0.54256(4), b=1.8552(1), c=1.2129(1) nm, β=94.91(1)°, V=1.2163(2) nm³, Z=4, ϱ=1.836 g⋅cm⁻³, R_all =0.069. Triazidotrinitro benzene has a remarkably high density (1.84 g⋅cm⁻³). The standard heat of formation of compound 1 was computed at B3LYP/6‐31G(d, p) level of theory to be ΔH°_f=765.8 kJ⋅mol⁻¹ which translates to 2278.0 kJ⋅kg⁻¹. The expected detonation properties of compound 1 were calculated using the semi‐empirical equations suggested by Kamlet and Jacobs: detonation pressure, P=18.4 GPa and detonation velocity, D=8100 m⋅s⁻¹.     

Application of FTIR spectroscopy for structural characterization of ternary poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes

The FTIR spectroscopic technique was used in the study of ternary polymer–metal complexes containing two polyelectrolytes of opposite charge and metal ions. The structure of the ternary (PAA‐Fe³⁺‐PVP) complexes was examined by following the changes in their infrared spectra. It was found that the shapes of the absorption bands of the resultant compounds are influenced by the presence of Fe³⁺. According to this result it was suggested that two types of structure which differ in the composition are formed, one of which results from the coordination of Fe³⁺ with PAA‐PVP complex and the other is due to the formation of Fe³⁺ polycarboxylate. Comparison between the spectrum of PAA‐PVP complex and those of the compounds resulted from the reaction between the two opposite charged electrolytes, PAA and PVP and each of the divalent metal chlorides NiCl₂, CoCl₂, CuCl₂, and ZnCl₂) led to the conclusion that a reaction took place between the divalent transition metal chlorides and the extent of reaction depends on the nature of metal ions and PAA‐PVP complex. The FTIR spectra of the precipitate resulted from the mixtures of PAA‐PVP and Ni(NO₃)₂ or Sr(NO₃)₂ were investigated. It was noted that the addition of Ni(NO₃)₂ or Sr(NO₃)₂ to the mixture of the electrolytes of PAA and PVP provoked appreciable changes in the characteristic spectral features of the complex resulting from the interaction of the metal ions with the polymer–polymer complex. The FTIR spectra of the precipitate resulted from the reaction between CeCl₃, ErCl₃, and LaCl₃ were also investigated. It was concluded that a reaction took place between the rare earth metals and the PPC. This means that ternary polymer–metal–polymer complexes were formed. The extent of changes in the spectral features differs from metal to metal according to the nature of metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Laser Ignition of Nano‐Composite Energetic Loose Powders

Laser ignition experiments were conducted to better understand parameters that influence ignition of energetic materials. A Nd:YAG laser (10 ms, 1.5 J, 3 mm spot diameter) was used to heat the top surface of an energetic powder composed of nanometric aluminum (Al) combined stoichiometrically with an oxidizer (copper oxide (CuO), iodine pentoxide (I₂O₅), polytetrafluoroethylene (C₂F₄), molybdenum trioxide (MoO₃) or iron oxide (Fe₂O₃)). Ignition delay time was calculated as the difference between first light of the laser’s flash lamp and the energetic material. Results show that laser energy required for ignition is dependent on pre‐ignition reactions, phase change/decomposition temperatures, confinement, and laser absorbance.     

Study of Some Low Temperature Gas‐Generating Compositions

Some low temperature gas‐generating compositions, comprised of guanidine nitrate (GN), basic cupric nitrate (BCN), and ferric oxide (Fe₂O₃), were studied herein. The thermal decomposition properties and burning characteristics of GN/BCN/Fe₂O₃ mixtures were investigated by thermogravimetry/differential scanning calorimetry (TG/DSC), burning temperature measurements, automatic calorimetry, and X‐ray diffraction (XRD). This study showed that the maximum burning temperature of GN/BCN/Fe₂O₃ mixture (613 °C) was 31 % lower than that of GN/BCN mixture and the corresponding heat of combustion (2647 J g⁻¹) decreased by 15 %. When the GN/BCN/Fe₂O₃ mixtures were burning, Fe₂O₃ did not directly react with GN but with Cu (or CuO), which was produced by reaction between GN and BCN. The combustion process of GN/BCN/Fe₂O₃ grains could be divided into four stages: pre‐heated, condensed, combustion, and cooling.     

The Thermal Behavior of the Zinc Complexes as a Non‐Azide Gas Generant for Safer Driving — Zn Complexes of the Carbohydrazide and Semicarbazide

The thermal behavior was investigated for the Zn complexes of carbohydrazide and semicarbazide with Sr(NO₃)₂ and 10% CuO as the oxidizing agent. In both complexes, there was little difference in the various combustion characteristics. The combustion reactivity was relatively low compared with the case of using other oxidizing agents, such as KBrO₃, etc. But the participation of CuO in the reaction was supposed to be different based on the analysis of the combustion residue. As for the gas evolution behavior, the evolution of N₂, NH₃, N₂O, NO_x and CO_x gases was confirmed upon ignition at 500°C in both complexes (no H₂O analysis). It was interesting that CO gas not evolved from the semicarbazide complex. It was clear that the combustion reactivity and the gas evolution behavior vary in both complexes in spite of the same skeleton and similar oxygen balance.     

In Vitro Degradation and Conversion of Melt‐Derived Microfibrous Borate (13‐93B3) Bioactive Glass Doped with Metal Ions

Microfibrous melt‐derived bioactive glasses based on a borate 13‐93B3 composition are showing a considerable capacity to heal chronic soft tissue wounds in humans and animals. Metal ion dopants in borate 13‐93B3 microfibers can be beneficial for healing soft tissue wounds and bone defects but their role and delivery have received little attention. In this study, the effect of selected metal ion dopants on the degradation and conversion of 13‐93B3 microfibers in simulated body fluid at 37°C was investigated. Two groups of microfibers (diameter = 0.2–3 μm) composed of 13‐93B3 glass (composition 6 Na₂O, 12 K₂O, 5 MgO, 20 CaO, 4 P₂O₅, 53 B₂O₃, wt%) doped with (1) CuO (0.4 wt%) + ZnO (1.0 wt%); and (2) CuO (0.4 wt%) + ZnO (1.0 wt%) + Fe₂O₃ (0.4 wt%) + SrO (2.0 wt%) were studied. The metal ion dopants had little effect on the degradation of the parent 13‐93B3 glass microfibers and their conversion to an amorphous calcium phosphate (ACP) product but they inhibited the crystallization of the ACP to HA. The release of Cu and Sr ions from the glass into the medium was considerably higher than Zn and Fe ions which were retained mainly in the ACP or HA product. These results are pertinent to the design of borate bioactive glasses for optimum healing of soft tissue wounds and bone.     

Temperature‐Programmed Oxidation of Soot in a Hybrid Catalysis‐Plasma System

Non‐thermal plasma (NTP) technology was applied to promote the temperature‐programmed oxidation (TPO) of soot over a perovskites type of La_0.8K_0.2MnO₃ catalyst. The O radicals originating from the decomposition of O₂, as well as NO dissociation if nitrogen oxide were involved, reduce the ignition temperatures of soot. In NO‐O₂‐He, for example, the ignition temperature decreased to 240 °C from 290 °C as the voltage increased from 0 kV to 15 kV. The higher voltage also benefited the adsorption of NO molecules onto the catalyst surface (NO_ad). As a result, the maximum N₂/NO ratio (conversion ratio of NO into N₂) rose from 23 % to 53 %. Some of the NO molecules were dissociated into N and O radicals in plasma, and hence, the N₂/NO ratio was further enhanced due to the combination of N atoms. In any case, the redox process between NO_x and soot proved to be important in soot oxidation.     

Processing of 0.7BaTiO3–0.3BiScO3 Solid‐Solution Coatings

Coatings with the 0.7BaTiO₃–0.3BiScO₃ solid‐solution composition were formed on palladium and single‐crystal (001) SrTiO₃ substrates using a polymeric metal citrate precursor. Solutions of TiOCl₂, Ba(NO₃)₂, Sc(NO₃)₃, and Bi(NO₃)₃ were mixed with citric acid and polymerized with ethylene glycol. Stable mixed‐metal citrate solutions were formed at pH > 9 and used for coatings. The phase and composition of powders and coatings were characterized using DTA, TGA, SEM, TEM, and X‐ray diffraction. Single‐phase cubic 0.7BaTiO₃–0.3BiScO₃ solid solutions formed at 600°C. Coatings on Pd using precursors doped with 5 wt% lithium nitrate were dense after sintering at 950°C/1 h. Coatings without lithium nitrate required 1050°C/50 h to densify. Coatings on SrTiO₃ heat‐treated at 1150°C were dense but formed a (Sc,Ti)‐rich second phase.     

Structural and Theoretical Investigations of 3,4,5‐Triamino‐1,2,4‐Triazolium Salts

Reactions using the high nitrogen heterocycle 3,4,5‐triamino‐1,2,4‐triazole (guanazine) with strong acids (HNO₃, HClO₄, and “HN(NO₂)₂”) resulted in a family of highly stable salts. All of the salts were characterized using spectroscopic as well as single crystal X‐ray diffraction studies. The X‐ray structures were compared to that obtained from theoretical calculations (MP2/6‐311+G(d, p) level). Initial safety testing (impact, friction) was carried out on all of the new materials.     

Synergistic extraction and separation study of rare earth elements from nitrate medium by mixtures of sec‐nonylphenoxy acetic acid and 2,2′‐bipyridyl

BACKGROUND: Synergistic extraction has been proven to enhance extractability and selectivity. Numerous types of synergistic extraction systems have been applied to rare earth elements, among which sec‐nonylphenoxyacetic acid (CA100) has proved to be an excellent synergistic extractant. In this study, the synergistic enhancement of the extraction of holmium(III) from nitrate medium by mixtures of CA100 (H₂A₂) with 2,2′‐bipyridyl (bipy, B) in n‐heptane has been investigated. The extraction of all other lanthanides (except polonium) and yttrium by the mixtures in n‐heptane has also been studied. RESULTS: Mixtures of CA100 and bipy have significant synergistic effects on all rare earth elements, for example holmium(III) is extracted as Ho(NO₃)₂HA₂B with the mixture instead of HoH₂A₅, which is extracted by CA100 alone. The thermodynamic functions, ΔH^o, ΔG^o, and ΔS^o have been calculated as 2.96 kJ mol^?1, ? 6.23 kJ mol^?1, and 31.34 J mol^?1 K^?1, respectively. CONCLUSION: Methods of slope analysis and constant molar ratio have been successfully applied to study the synergistic extraction stoichiometries of holmium(III) by mixtures of CA100 and bipy. Mixtures of these extractants have also shown various synergistic effects with other rare earth elements, making it possible to separate them. Thus CA100 + bipy may be used to separate yttrium from other lanthanides at appropriate ratios of the extractants. Copyright © 2011 Society of Chemical Industry     

High‐performance HTLcs‐derived CuZnAl catalysts for hydrogen production via methanol steam reforming

A series of CuZnAl oxide‐composite catalysts were prepared via decomposition of CuZnAl hydrotalcite‐like compounds (HTLcs). The catalysts derived from CuZnAl HTLcs (Cu: 37%, Zn: 15%, Al: 48% mol; using metal nitrate or acetate precursors) at 600°C provided excellent activity and stability for the methanol steam reforming. CuZnAl HTLcs were almost decomposed completely at 600°C to form highly dispersed CuO with large specific surface area while forming CuAl₂O₄ spinel that played a key role in separating and stabilizing the nano‐sized Cu and ZnO during the reaction. The CuZnAl catalyst prepared from metal acetates could highly convert H₂O/MeOH (1.3/1, mol/mol) mixture into hydrogen with only ～0.05% CO at 250°C or ～0.005% at 210°C. It is evidenced that the former afforded stronger Cu‐ZnO interaction, which might be the intrinsic reason for the significant promotion of catalyst selectivity. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Synthesis of modified catalyst and stabilization of CuO/NH4‐ZSM‐5 for conversion of methanol to gasoline

In this article, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over CuO/ NH₄‐ZSM‐5(3,5,7,9%) catalysts prepared via sono‐chemistry methods. In order to improve, copper oxide can be used as a booster on NH₄‐ZSM‐5 this catalyst property. Accordingly, the conversion process of Methanol to Gasoline (MTG) was conducted under a pressure of 1 atm and temperature of 400°C by a fixed‐bed reactor on copper oxide catalysts which were prepared based on synthetic NH₄‐ZSM‐5. The synthetic catalyst was investigated by such analyses as BET, XRD, FT‐IR, and SEM. Formation of copper oxide phase and proper distribution of copper oxide were proven on the basic level of using XRD analysis. BET analysis showed the reduction in catalyst level and SEM images depicted the proper distribution of particles. The present investigation is to study the effect of CuO loading on NH4‐ZSM‐5 support for conversion of methanol to gasoline range hydrocarbons. A series of CuO/ NH4‐ZSM‐5 catalysts were prepared, characterized, and experimented for their performance on methanol conversion and hydrocarbon yield.     

Ethanol perm‐selective B‐ZSM‐5 zeolite membranes from dilute solutions

Boron‐substituted MFI (B‐ZSM‐5) zeolite membranes with high pervaporation (PV) performance were prepared onto seeded inexpensive macroporous α‐Al₂O₃ supports from dilute solution and explored for the separation of ethanol/water mixtures by PV. The effects of several parameters on microstructures and PV performance of the B‐ZSM‐5 membranes were examined systematically, including the seed size, synthesis temperature, crystallization time, B/Si ratio, H₂O/SiO₂ ratio and silica source. A continuous and compact B‐ZSM‐5 membrane was fabricated from solution containing 1 tetraethyl orthosilicate/0.2 tetrapropylammonium hydroxide/0.06 boric acid/600 H₂O at 448 K for 24 h, showing a separation factor of 55 and a flux of 2.6 kg/m² h along with high reproducibility for a 5 wt % ethanol/water mixture at 333 K. It was demonstrated that the incorporation of boron into mobile five (MFI) structure could increase the hydrophobicity of B‐ZSM‐5 membrane evidenced by the improved contact angle and amount of the adsorbed ethanol, and thus enhance the PV property for ethanol/water mixtures. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2447–2458, 2016     

Studies on the solvent extraction of rare earths from nitrate media with a combination of di‐(2‐ethylhexyl)phosphoric acid and sec‐octylphenoxyacetic acid

BACKGROUND: Di‐(2‐ethylhexyl)phosphoric acid (D2EHPA, H₂A₂) has been used extensively in hydrometallurgy for the extraction of rare earths, but it has some limitations. Synergistic extraction has attracted much attention because of its enhanced extractabilities and selectivities. In the present study, sec‐octylphenoxyacetic acid (CA12, H₂B₂) was added into D2EHPA systems for the extraction and separation of rare earths. The extraction mechanism of lanthanum with the mixtures and the separation of lanthanoids and yttrium were investigated. RESULTS: The synergistic enhancement coefficient for La³⁺ extracted with D2EHPA + CA12 was calculated as 3.63. La³⁺ was extracted as La(NO₃)₂H₂A₂B with the mixture. The logarithm of the equilibrium constant was determined as 0.80. The thermodynamic functions, ΔH, ΔG, and ΔS were calculated to be 4.03 kJ mol^?1, ? 1.96 kJ mol^?1, and 20.46 J mol^?1 K^?1, respectively. The mixtures have synergistic effects on Ce³⁺, Nd³⁺, and Y³⁺, with an especially strong synergistic effect on Y³⁺. Neither synergistic nor antagonistic effects on Dy³⁺ and weak antagonistic effects on Lu³⁺ were found. CONCLUSION: Mixtures of D2EHPA and CA12 exhibit evident synergistic effects when used to extract La³⁺ from nitric solution. The stoichiometries of the extracted complexes have been determined by graphical and numerical methods to be La(NO₃)₂H₂A₂B with the mixture. The extraction is an endothermic process. The mixture exhibits different extraction effects on rare earths, which provides possibilities for the separation of Y³⁺ from Ln³⁺ at a proper ratio of D2EHPA and CA12. Copyright © 2008 Society of Chemical Industry     

Ethylene/1‐octadecene copolymerization using [η5:η1‐C5Me4‐4‐R1‐6‐R‐C6H2O]TiCl2 catalysts

Copolymerization of ethylene with 1‐octadecene was studied using [η⁵:η¹‐C₅Me₄‐4‐R₁‐6‐R‐C₆H₂O]TiCl₂ [R₁ = ^tBu (1), H (2, 3, 4); R = ^tBu (1, 2), Me (3), Ph (4)] as catalysts in the presence of Al(i‐Bu)₃ and [Ph₃C][B(C₆F₅)₄]. The effect of the concentration of comonomer in the feed and Al/Ti molar ratio on the catalytic activity and molecular weight of the resultant copolymer were investigated. The substituents on the phenyl ring of the ligand affect considerably both the catalytic activity and comonomer incorporation. The 1 /Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄] catalyst system exhibits the highest catalytic activity and produces copolymers with the highest molecular weight, while the 2 /Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄] catalyst system gives copolymers with the highest comonomer incorporation under similar conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal decomposition of pyrotechnic mixtures containing either aluminum or magnesium powder as fuel

Thermal behavior of energetic materials is critical to safe production, storage, handling or even demilitarization. In this work, the thermal behavior of Al, Mg, CuO, KMnO₄ and also three mixtures containing Al + CuO, Mg + CuO and Mg + KMnO₄ were studied experimentally using differential scanning calorimetry and thermogravimetry. These mixtures are sometimes used as pyrotechnic mixtures in military industries. Also, the influence of different heating rates (5, 10, 15 and 20 °C/min) on the DSC behavior of the mixtures was verified. The results showed that as the heating rate was increased, melting points and ignition temperatures of the mixtures were increased. On the other hand, TG-DSC analysis for Mg + KMnO₄ mixture indicates that this mixture melts at 283.0 °C and decomposed at 292.1 °C. By replacing KMnO₄ with CuO as the oxidizer of the magnesium, these temperatures enhanced to 368.7 °C and 408.3 °C, respectively. However, replacing Mg with Al in the Mg/CuO mixture decreases the melting and ignition temperatures of the mixture to 231.4 °C and 271.9 °C, respectively. The activation energy for each pyrotechnic mixture was computed. Also, the values of ΔS^#, ΔH^# and ΔG^# of their reaction were calculated.     

Novel and Mild Route to Phthalocyanines and 3‐Iminoisoindolin‐1‐ones via N,N‐Diethylhydroxylamine‐Promoted Conversion of Phthalonitriles and a Dramatic Solvent‐Dependence of the Reaction

Refluxing a mixture of phthalonitrile C₆R¹R²R³R⁴(CN)₂ 1 (R¹–R⁴=H), or its substituted derivatives 2 (R¹, R³, R⁴=H, R²=Me), or 3 (R¹, R⁴=H, R², R³=Cl) (1 equiv.) and N,N‐diethylhydroxylamine, Et₂NOH, (4 equivs.) in methanol for 4 h results ( Route A ) in precipitation of the symmetrical ( 6 and 8 ) and an isomeric mixture of unsymmetrical ( 7 ) phthalocyanines, isolated in good (55–65 %) yields. The reaction of phthalonitriles 1 , 2 , or 4 (R¹, R³, R⁴=H, R²=NO₂) (4 equivs.) with Et₂NOH (8 equivs.) in the presence of a metal salt MCl₂ (M=Zn, Cd, Co, Ni) (1 equiv.) in n‐BuOH or without solvent results in the formation of metallated phthalocyanine species ( 9 – 17 ). Upon refluxing in freshly distilled dry chloroform, phthalonitrile 1 or its substituted analogues 2 , 3 or 5 (R¹–R⁴=F) (1 equiv.) react with N,N‐diethylhydroxylamine (2 equivs.) affording 3‐iminoisoindolin‐1‐ones 18 – 21 ( Route B ) isolated in good yields (55–80 %). All the prepared compounds were characterized with C, H, and N elemental analyses, ESI‐MS, IR, and compounds 18 – 21 also by 1D (¹H, ¹³C{¹H}), and 2D (¹H,¹⁵N‐HMBC and ¹H,¹³C‐HMQC, ¹H,¹³C‐HMBC) NMR spectroscopy.     

Asymmetric 1,3‐Dipolar Cycloaddition Reaction between α,β‐Unsaturated Aldehydes and Nitrones Catalyzed by Well‐Defined Iridium or Rhodium Catalysts

Reaction of the complexes (S_M,R_C)‐[(η⁵‐C₅Me₅)M{(R)‐Prophos}(H₂O)](SbF₆)₂ (M=Rh, Ir) with α,β‐unsaturated aldehydes diastereoselectively gave complexes (S_M,R_C)‐[(η⁵‐C₅Me₅)M{(R)‐Prophos}(enal)](SbF₆)₂ which have been fully characterized, including an X‐ray molecular structure determination of the complex (S_Rh,R_C)‐[(η⁵‐C₅Me₅)Rh{(R)‐Prophos}(trans‐2‐methyl‐2‐pentenal)](SbF₆)₂. These enal complexes efficiently catalyze the enantioselective 1,3‐dipolar cycloaddition of the nitrones N‐benzylideneaniline N‐oxide and 3,4‐dihydroisoquinoline N‐oxide to the corresponding enals. Reactions occur with excellent regioselectivity, perfect endo selectivity and with enantiomeric excesses up to 94 %. The absolute configuration of the adduct 5‐methyl‐2,3‐diphenylisoxazolidine‐4‐carboxaldehyde was determined through its (R)‐(−)‐α‐methylbenzylamine derivative.