Selective Extraction of N‐Heterocyclic Precursors of 1,3,5,7‐Tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) Using Molecularly Imprinted Polymers

N‐heterocyclic compounds are key nitration precursors for some high energy density explosives such as 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX). Nitration of 1,3,5,7‐tetraacetyl‐1,3,5,7‐tetraazacyclooctane (TAT) yields HMX in high yields and purity. However, the analogue 1,3,5‐triacetyl‐1,3,5‐triazacyclohexane (TRAT) is easily co‐produced via the condensation of acetonitrile and 1,3,5‐trioxan. To selectively extract TAT from a mixture of TAT and TRAT, the molecular imprinting technology (MIT) was developed in this study. The capacity of the dry polymer is 16 mg g⁻¹ and the recovery surpasses 75 %.     

Analysis of Polar Precursors of 1,3,5,7‐Tetranitro‐1,3,5,7‐tetrazocine (HMX) Using Hydrophilic Interaction Chromatography

Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) is currently one of the most widely used explosives. 1,3,5,7‐Tetraacetyl‐1,3,5,7‐tetraazacyclooctane (TAT) is an attractive precursor for the synthesis of HMX; the nitration of this key precursor results in both high yield and purity under mild condition. TAT can be prepared either by acetylation of 2,6‐diacetyl‐pentamethylenetetramine (DAPT) or by the condensation of ACN and 1,3,5‐trioxane. However, TAT and DAPT are polar compounds, and are difficult to analyze using reverse phase liquid chromatography. Herein, a chromatography method for the direct separation of these polar compounds was developed using hydrophilic interaction chromatography (HILIC) using a Venusil HILIC column, with ACN/water (95/5, v/v) as the mobile phase. The chromatographic analysis and identification of these polar compounds provide valuable information for the optimization of the synthetic process of TAT.     

p-Chlorostyrene oligomers. Preparation,structure, and stereochemistry

The dimer and trimer obtained by the pyrolysis of poly(p-chlorostyrene) were 2,4-di(p-chlorophenyl)-1-butene and 2,4,6-tri(p-chlorophenyl)-1-hexene, respectively, while those obtained by the cationic oligomerization of p-chlorostyrene were trans-1,3-di(p-chlorophenyl)-1-butene and a diastereomeric pair of trans-1,3,5-tri-(p-chlorophenyl)-1-hexene.     

Donorsubstituierte 2,4-Diazacyclopentadienone und indigoide 1,3,5,7-Tetraazafulvalene

Donor Substituted 2,4-Diazacyclopentadienones and Indigoid 1,3,5,7-Tetraazafulvalenes Hydrolysis of tris(diethylamino)imidazolylium chloride gives rise to 2,5-bis-diethyl-amino-4H-imidazolin-4-one; thiolysis leads, depending on conditions, to 2,5-bis-diethylamino-4H-imidazolin-4-thione or potassium 2,6-bis-diethylamino-1,3,5,7-tetraazafulvalene-4,8-dithiolate. The latter can be protonated to form green 2,6-bis(dimethylamino)-3,4,7,8-tetrahydro-1,3,5,7-tetraaza-fulvalen-4,8-dithione, a new indigoid compound, and alkylated to give blue 2,6-bis-diethylamino-4,8-bis-alkylthio-1,3,5,7-tetraazafulvalenes. Treatment of 2,5-bis-diethylamino-4H-imidazolin-4-thione with copper furnishes 2,6,4,8-tetrakis-diethylamino-1,3,5,7-tetraazafulvalene. – Oxidation of 2,6-bis-dimethylamino-3,4,7,8-tetrahydro-1,3,5,7-tetraazafulvalen-4,8-dithione gives rise to (2,2′-bis-diethylamino-4,4′-bi(4H-imidazol)-5,5′-dithione, corresponding to dehydroindigo, and reduction leads to a colorless compound, corresponding to leucoindigo.     

Synthesis of the Ladder Polymers by the Reaction of Catalytic Dehydrocondensation

Abstract

The heterofunctional condensation of cis-1,3.5,7-tetrahydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane with dimethylchlorosilane has been studied.

It was established that when the reaction proceeds under mild conditions tetraphenylcyclotetrasiloxane incompletely substituted with dimethylsiloxy groups is obtained, i.e., 1,3,5-tris(dimethylsiloxy)-7-hydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane, while under certain conditions 1,3,5,7-tetrakis(dimethylsiloxy)-1,3,5,7-tetraphenylcyclotetrasiloxane is formed.

The catalytic dehydrocondensation of 1,3,5-tris(dimethylsiloxy)-7-hydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane both in a dilute and concentrated solutions in the presence of platinochlorohydric acid as a catalyst has been studied. It was shown that the reaction proceeds both by the mechanism of intramolecular cyclization with formation of a bicyclic compound and intermolecularly with formation of a tricyclic compound.

The catalytic dehydrocondensation of 1,3,5,7-tetrakis-(hydriddimethylsiloxy)-1,3,5,7-tetraphenylcyclotetrasiloxane with cis-1,3,5,7-tetrahydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane and with oligotetrols (m = 5, 10) was also studied. The reaction order, activation energies and dehydrocondensation rate constants were found.

It was established that with an increase in the length (m) of the oligotetrols the degree of catalytic dehydrocondensation is reduced. It was shown that if the platinochlorohydric acid catalyst is replaced by anhydrous powdered caustic potassium a different configuration of the cyclotetrasiloxane skeleton is realized in polymers.     

New adducts of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)

A new series of relatively stable adducts of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with derivatives of pyridine-N-oxide were prepared. In addition, relative stable new adducts of HMX were prepared with 5-membered, 6-membered, and condensed-ring heterocyclic compounds. Most of the adduct-forming compounds (AFC's) contain an oxygen and/or nitrogen heteroatom, while several contain a sulfur heteroatom. Most of the adducts are equimolar with HMX; however, several contain 2 moles of AFC per mole of HMX and other ratios of AFC:HMX. Some properties of the new adducts are presented.     

Study on the Mechanism of the Acetolysis of Hexamethylenetetramine

The acetolysis of hexamethylenetetramine (hexamine) to give 3,7-diacetyl-1,3,5,7-tetraaza-[3.3.1]-bicyclononane (DAPT), 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) and 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT) was studied. NMR tracing showed the courses of acetolysis, the effects of the reaction conditions on its directions, and the evidence that the methylene degraded from hexamine was the formaldehyde. Based on these results, the acetolysis mechanism was proposed. The comparison of the acetolysis with the nitrolysis of hexamine showed that the two reactions experienced the similar courses, which would be useful for searching out a way to improve the yield of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) in Bachmann process.     

Cationic Heterogeneous Copolymerization of Octamethylcyclotetrasiloxane with 1,3,5,7-Tetramethyl-1,3,5,7-tetravinylcyclotetra-Siloxane: Optimization of Reaction Conditions

Copolymerization of octamethylcyclotetrasiloxane (D₄) with 1,3,5,7-tetrametyl-1,3,5,7-tetravinylcyclotetrasiloxane (V₄) by heterogeneous acid catalysis has been carried out. In order to find the optimal conditions of the reaction, a second-order experimental design was performed with reaction time, reaction temperature, amount of catalyst, and the initial molar fraction of the monomers as independent parameters. By data processing, response surfaces of monomer conversion and copolymer composition were obtained, which were studied by eigenvalues analysis and by plotting in 2-D fields. It was found that the most important factors of influence were reaction temperature for the monomer conversion and the initial monomer molar fraction for the copolymer final composition.     

The involvement of 1,6-diphenyl-1,3,5-hexatriene and 1,8-diphenyl-1,3,5,7-octatetraene in the radical polymerization of methyl methacrylate

Summary The , -diphenyl derivatives of 1,3,5-hexatriene and 1,3,5,7-octatetraene strongly retard the radical polymerization of methyl methacrylate (MMA); the effects are greater when initiation is achieved with benzoyl peroxide than when azobisisobutyronitrile is used. The tetraene and the triene are respectively 575 and not less than 240 times as effective as MMA in capturing the benzoyloxy radical at 60°C.     

Chemical Transformation of Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) Induced by Low Energy Electron Beam Irradiation

The effects of 8.0×10⁻¹⁷ J (500 eV) and 3.2×10⁻¹⁹ J (2 eV) electrons on chemical structure of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) were studied in situ, under ultra‐high vacuum conditions using a combination of X‐ray photoelectron spectroscopy (XPS) and quadrupole mass spectrometry. XPS data indicated that electrons impact by 8.0×10⁻¹⁷ J for 30 s caused a decrease in nitro group concentration, and a little shift in the binding energy of the nitrogen 1s peak. Such a phenomenon was found at very low kinetic energy (3.2×10⁻¹⁹ J) with time evolution. Quadrupole mass spectrometry detected gas desorption after electron irradiation included H₂O and H₂ mostly. Microscopy‐IR spectroscopic investigations also proved that the intensity of nitro groups of HMX after irradiation decreased compared with those of the pristine HMX. We attributed the structure changes obtained by XPS and IR spectroscopy result in a chemical transformation, which was associated with low‐energy dissociative electron attachment (DEA) of surface contaminants followed by deoxidization reactions to form the product molecules.     

New adducts of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX)

Relatively stable equimolar adducts of 1,3,5-trinitro-1,3,5-triazacyclohexane were prepared with 2,6-lutidine-N-oxide, 4-hydroxy-1-butanesulfonic acid δ-sultone (1,4-butane sultone), and 2,2,6,6-tetramethyl-4-piperidone-1-oxyl. Only the last adduct is selective for RDX; the others also form adducts with 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane. A very labile RDX adduct is formed with tetrahydrothiophene-1-oxide. Some properties of the new adducts are presented.     

Sensitivity and Performance of Energetic Materials

This paper provides an overview of the main developments over the past nine years in the study of the sensitivity of energetic materials (EM) to impact, shock, friction, electric spark, laser beams, and heat. Attention is also paid to performance and to its calculation methods. Summaries are provided of the relationships between sensitivity and performance, the best representations for the calculation methods of performance being the volume heat of explosion or the product of crystal density and the square of detonation velocity. On the basis of current knowledge, it is possible to state that a single universal relationship between molecular structure and initiation reactivity does not yet exist. It is confirmed that increasing the explosive strength is usually accompanied by an increase in the sensitivity. In the case of nitramines this rule is totally valid for friction sensitivity, but for impact sensitivity there are exceptions to the rule, and with 1,3,5‐trinitro‐1,3,5‐triazepane, 1,3,5‐trinitro‐1,3,5‐triazinane, β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane, and the α‐, β‐ and ε‐polymorphs of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane the relationship works in the opposite direction. With respect to the QSPR approach there might be reasonably good predictions but it provides little insight into the physics and chemistry involved in the process of initiation.     

The Nitrolysis Mechanism of 3,7‐Dinitro‐1,3,5,7‐tetraazabicyclo[3,3,1]nonane

Two intermediates, 1,5‐dinitroso‐3,7‐dinitro‐1,3,5,7‐tetraazacyclooctane (DNDS) and 1‐nitroso‐3,5,7‐trinitro‐1,3,5,7‐tetraazacyclooctane (MNX), were isolated and characterized in the synthesis of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) from the nitrolysis of 3,7‐dinitro‐1,3,5,7‐tetraazabicyclo[3,3,1]nonane (DPT) for the first time. When the nitrolysis of DPT was slowed down, two intermediates were detected with HPLC. It was proposed that electrophilic NO₂⁺ and NO⁺ from HNO₃ and N₂O₄ might attack nitrogen atoms at positions 3 and 7 of DPT to form the cations of the intermediates, then nucleophilic H₂O attacked the bridge carbon atoms of DPT to produce the intermediates, which were oxidized to form HMX.     

用LC/APCI/MS方法检测粉尘中的炸药成分

采用高选择性和灵敏度的LC(液相色谱)/APCI(大气压化学电离源)/MS(质谱)方法定量分析粉尘样品中的HMX、RDX、PETN、CE、NQ和TNT。采用ASE萃取,GPC净化浓缩作为前处理方法,在粉尘中分别添加所测炸药组分,用丙酮作为ASE萃取溶剂,乙酸乙酯和环己烷(体积比为1∶1)作为GPC净化时的流动相并抛弃杂质500s,收集1 520s。在LC/MS分析时,通过在流动相中添加1mmol/L甲酸与样品形成[M+HCOO]-的甲酸加合离子。结果表明,HMX、RDX、PETN、CE、NQ、TNT的方法检测限分别为0.78,1.44,1.69,0.77,1.06,1.72ng/mL,回收率为49.0%～88.4%,相对标准偏差为3.5%～10.3%。该方法可以用来系统排查及定量分析爆炸残留物及环境样品中的NQ、RDX、PETN、CE、HMX、TNT成分。     

Transition Structures of the Electrocyclic Reactions of cis,cis,cis-1,3,5-Cyclooctatriene

The electrocyclic reactions of cis,cis,cis-1,3,5-cyclooctatriene have been studied using ab initio molecular orbital theory. cis,cis,cis-1,3,5-cyclooctatriene can undergo an electrocyclic ring opening in a conrotatory fashion to form cis,cis-1,3,5,7-octatetraene and a disrotatory electrocyclization to form bicyclo[4.2.0]octa-2,4-diene. The transition structures for these electrocyclic reactions have been located. Geometry optimizations employed restricted Hartree-Fock calculations and the 3–21G and 6–31G* basis sets. Electron correlation energies were calculated using second-order, and in some cases fourth-order, Møller-Plesset theory. Scaled RHF/6–31G* force constants were employed in the prediction of secondary deuterium isotope effects for the conrotatory ring opening. The ground state of cis,cis,cis-1,3,5-cyclooctatriene exists in a twist-boat conformation with staggering at the saturated linkage. The transition structure for the conrotatory electrocyclic ring opening to form cis,cis-1,3,5,7-octatetraene has a helical structure, which has implications for the stereoselectivities of ring closure of 1-substituted-cis,cis-1,3,5,7-octatetraenes. The disrotatory transition structure for the electrocyclization to form bicyclo[4.2.0]octa-2,4-diene is strongly distorted from C_s symmetry, in contrast to the transition structure for the disrotatory electrocyclization of cis-1,3,5-hexatriene. This distortion is caused by staggering about the saturated linkage.     

Synthesis and chemical modification of poly(divinylsiloxane)

Hexavinylcyclotrisiloxane(I) has been prepared by reaction of divinyldichlorosilane with DMSO and triethylamine. Anionic ring-opening polymerization (AROP) of I catalyzed by dilithio diphenylsilanediolate yields high molecular weight poly(divinylsiloxane)(II) with a narrow molecular weight distribution. Similarly, narrow molecular weight distribution poly(vinylmethylsiloxane)(III) has been prepared by AROP of 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane(IV) initiated by dilithio diphenylsilanediolate. On the other hand, III which has a broad molecular weight distribution has been synthesized by AROP of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane(V) catalyzed by phosphazene P₄-t-Bu superbase. Chemical modification of the C-C double bonds of II and III has been achieved by Pt-catalyzed hydrosilylation with 3,3,3-trifluoropropyldimethylsilane(VI) or 1H,1H,2H,2H-perfluorooctyldimethylsilane(VII). While Pt-catalyzed hydrosilylation reactions usually proceed in a regioselective anti-Markovnikov manner, Markovnikov addition is competitive in these examples.     

DFT Studies on a Series of Nitramines Containing Pyridine Ring

In this article, a series of nitramines containing pyridine ring were studied by density functional theory (DFT). The gas-phase heats of formation were predicted based on the isodesmic reactions and the condensed-phase heats of formation and heats of sublimation were estimated with the Politzer's approach. The detonation velocity and pressure were calculated using the empirical Kamlet-Jacobs equation. Many title compounds have better performance than RDX (hexahydro-1,3,5-trinitro-1,3,5-trizine) and HMX (1,3,5,7-tetranitro-1,3,5,7- tetraazacyclooctane). The impact sensitivity was evaluated with the characteristic height (h₅₀). It is found that most of the studied compounds have lower sensitivities than CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12- hexaazaisowurtzitane). The crystal structures were predicted with the molecular mechanics method and optimized by the CA-PZ local density approximation of DFT. Analysis of the crystal energy gap indicates I-13, II-1, III-1, and IV-1 are nearly conductors and other compounds are semiconductors. For I-1～I-8 and I-11, the largest contribution to the valence bands is mainly from the p states of the C and N atoms in the pyridine and fused ring and for the other compounds, from the p states of the C and N atoms in the amino group and pyridine.     

金刚烷直接氧化制备金刚烷多元醇新工艺

引言金刚烷(三环[3.3.1.1]3,7癸烷)是一种周正对称、高度稳定的笼状饱和烃,它的4个桥头碳上的氢具有较强的化学反应能力,可以被选择性地取代引入相同或不同的基团,这使得分子的可设计性     

Study of Plastic Explosives based on Attractive Cyclic Nitramines Part I. Detonation Characteristics of Explosives with PIB Binder

Four plastic explosives based on energetic nitramines and a non‐energetic binder were prepared and studied. The nitramines were RDX (1,3,5‐trinitro‐1,3,5‐triazine), HMX (1,3,5,7‐tetranitro‐1,3,5,7‐tetrazine), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole) and HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ε‐CL‐20). The binder was in all cases polyisobutylene (PIB) as in the standard composition C‐4. These powerful plastic explosives were compared to standard PETN‐based commercially available explosives Semtex 1A and Sprängdeg m/46. The detonation velocities were experimentally measured and compared to the ones calculated by the Kamlet–Jacobs method, CHEETAH and EXPLO5 Codes. The experimental detonation velocities as well as the calculated detonation parameters decrease in the following order: HNIW‐PIB>HMX‐PIB≥BCHMX‐PIB>RDX‐PIB>Sprändeg m/46≥Semtex 1A. Urizar coefficients for the various binders were calculated from experimental data.     

Use of NMR spectrometry for studying the acetolysis of hexamethylenetetramine III. The reaction between hexamethylenetetramine and acetic anhydride to form TRAT

The acetolysis of hexamethylenetetramine (HA) to form 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT) has studied by NMR. It was found that this reaction experienced two different courses. HA turned to TRAT through the intermediate 3,7-diacetyl-1,3,5,7-tetraaza-[3.3.1]-bicyclononace (DAPT), and HA converted at first to an intermediate M₁, which gave TRAT through another intermediate M₂ in the presence of water. Based on the ¹H and ¹³C spectra, the change in the spectra with reaction and the possibility of reaction, we assumed both the structure of M₂ and its reaction mechanism.