A LC-MS method allowing the analysis of HMX and RDX present at the picogram level in natural aqueous samples without a concentration step

The introduction of chloroform into the nebulising gas of a LC/MS electrospray interface (ESI), in a perfectly controlled way, leads to the formation of intense adducts ([M+Cl]⁻) when a mobile phase containing HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane or octogen) and RDX (1,3,5-trintro-1,3,5-triazacyclohexane or hexogen) is eluted. This LC/MS method allows the direct analysis of aqueous samples containing HMX and RDX at the pictogram level without a concentration step. The method is used to determine HMX and RDX concentrations in ground water samples from a military site.     

Mass spectral fragmentation pathways in RDX and HMX. A mass analyzed ion kinetic energy spectrometric/collisional induced dissociation study

A collisional induced dissociation study of 1,3,5-trinitro-1,3,5 triazacyclohexane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX) was carried out using mass analyzed kinetic energy spectrometry. High resolution mass spectra and mass analyzed ion kinetic energy/collisional induced dissociation spectra of RDX and HMX were recorded in the electron impact, chemical ionization and negative ion chemical ionization modes. Fragmentation pathways of the compounds investigated were determined in all three modes of ionization. It was found that a major part of the fragment ions in RDX and HMX originate from formation of the aduct ions [M+NO]⁺ and [M+NO₂]⁺ in electron impact and chemical ionization, and from [M+NO]^? and [M+NO₂]^? in negative chemical ionization, followed by dissociation.     

Nitrogen-15 studies of the mechanisms of acetolyses of hexamethylenetetramine and 3,7-diacetyl-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DAPT)

[¹⁵N₄]-Hexamethylenetetramine (Hexamine), and [¹⁵N₄]-3,7-diacetyl-1,3,5,7-tetraazabicyclo[3.3.1]nonane(DAPT) have been prepared starting from ¹⁵NH₃. Synthetic acetolysis reactions were performed using mixtures of pure [¹⁵N₄]- and [¹⁴N₄]-compounds and the destination of the nitrogen isotopes in the products was determined mass spectrometrically. The results show that relatively little isotopic mixing occurs in the acetolysis of hexamine to DAPT though the formation of some products with isotopic composition [¹⁴N₃¹⁵N₁] and [¹⁴N₁¹⁵N₃] indicates limited ring cleavage. However the more severe conditions used in the formation of 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT) give rise to considerable isotopic scrambling. The acetolysis of DAPT to give 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane occurs by selective cleavage of the methylene bridge.     

Separation of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane and 1,3,5‐trinitro‐1,3,5‐ triazacyclohexane by molecularly imprinted solid‐phase extraction

Synthesis of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane and 1,3,5‐trinitro‐1,3,5‐triazacyclohexane by the Bachmann process leads to a mixture of both. The separation of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane and 1,3,5‐trinitro‐1,3,5‐triazacyclohexane from their mixture is difficult because the sizes and physical properties of these homologous compounds are similar. For this purpose, seven molecularly imprinted polymers have been synthesized for each explosive, and a selective solid‐phase extraction procedure has been developed. A molecularly imprinted polymer, synthesized with 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane as the template, methacrylic acid as the monomer and trimethylolpropane trimethacrylate as the cross‐linking agent in a molar ratio of 1:8:8 showed the best separation capability. A packed cartridge containing this polymer can be reused for 23 solid‐phase extraction cycles without repacking, and the total separation capability toward 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane reached 6.81 mg per gram of polymer. 1,3,5‐Trinitro‐1,3,5‐triazacyclohexane was not detected in the separated 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane by high‐performance liquid chromatography and vice versa. This newly developed method had the advantages of high recovery (100%) and purity, environmental friendliness, and room temperature operability. This study showed that some molecularly imprinted polymers that cannot absorb target analytes well in the solvent in which the polymers were polymerized might have high‐binding capacity for the analytes and show imprinting effects in other solvents.     

Oxidative Aromatization of 1,3,5‐Trisubstituted 4,5‐Dihydro‐1H‐Pyrazoles Efficiently by Tetrabromine‐1,3,5,7‐Tetrazatricyclo[3.3.1.13,7]Decane Complex,Br4‐Tatcd,as a Novel Reagent both Under Microwave Irradiation and at Room Temperature

Oxidation of 1,3,5‐trisubstituted 4,5‐dihydro‐1H‐pyrazoles to the corresponding pyrazoles has been achieved by utilizing tetrabromine‐1,3,5,7‐tetrazatricyclo[3.3.1.1^3,7]decane complex, Br₄‐TATCD, in glacial acetic acid under microwave irradiation and conventional thermal condition at room temperature with excellent yields.     

The very far-infrared spectra of energetic materials and possible confusion materials using terahertz pulsed spectroscopy

We have measured the terahertz absorption spectra of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), pentaerythritol tetranitrate (PETN), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), 2,4,6-trinitrotoluene (TNT), the plastic explosives Semtex H, SX2, and Metabel, and a number of confusion materials using terahertz pulsed transmission spectroscopy. Spectral fingerprints were obtained from 3 to 133 cm⁻¹. The spectra of the plastic explosives are dominated by the spectral signatures of their explosive components due to low frequency vibrations and crystalline phonon modes. Importantly, the terahertz spectra of the confusion materials show no resemblance to the explosives spectra. The refractive indices obtained for the plastic explosives and confusion materials allowed us to derive reflectance spectra, which appear distinct and so suggest that terahertz reflection spectroscopy is a suitable tool for the detection of concealed explosives in security applications.     

Effective synthesis of <Emphasis Type="Italic">N</Emphasis>-substituted 1,3,5-dithiazinanes by reactions of <Emphasis Type="Italic">N</Emphasis>-methyl-1,3,5-dithiazinane and 1,3,5-trithiane with aromatic amines

A novel procedure has been developed for selective synthesis of N-aryl-1,3,5-dithiazinanes, 1,2,6,7-tetrahydro-3,5,1,7-benzodithiadiazonine, and 6,7-dihydro-1,3,5,7-benzotrithiazonine by reactions of aniline derivatives with N-methyl-1,3,5-dithiazinane or 1,3,5-trithiane in the presence of transition and rare earth metal salts and complexes.     

Bildung siliciumorganischer Verbindungen. 87. Das 2,8,9-Trioxa-1,3,5,7-tetrasilaadamantan

Formation of Organosilicon Compounds. 87. 2,8,9-Trioxa-1,3,5,7-Tetrasilaadamantane Hydrolysis of cis-cis-1,3,5-tribromo-1,3,5-tri-t-butyl-1,3,5-trisilacyclohexane yields the trisilanole 2 (mp. 205°C) which forms the tetrasilaadamantane 3 with SiCl₄/et₂NH. Hydrolysis of 3 yields 4 (Formulae see “Inhaltsübersicht”).     

Alkaline Decomposition of Cyclic Nitramines

Treatment of 1,3,5-trinitro-1,3,5-triazacyclohexane and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclo-octane with potassium hydroxide gives dipotassium salt of methylenedinitramine.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 130–132.Original Russian Text Copyright © 2005 by Il’yasov, Lobanova.     

Quantum chemical studies on the structure and detonation properties of the fused polynitrodiazoles: New high energy density molecules

In this study, we explore the possibility that fused polynitrodiazoles act as high energy density materials. Density functional theory calculations at the B3LYP/aug‐cc‐pVDZ level were performed to predict the structure, energy of explosion (≈1.68 kcal g^?1), density (≈1.98 g cm^?3), detonation velocity (≈9.50 km s^?1), and detonation pressure (≈41.50 GPa) of model molecules. The predicted properties have been found to be promising compared with 3,4,5‐trinitro‐1H‐pyrazole, 1,3,5‐trinitro‐1,3,5‐triazinane, and octahydro‐1,3,5,7‐tetranitro‐l,3,5,7‐tetraazocane. The nature of azoles of the molecule presumably determines the geometry, stability, sensitivity, density, and detonation performance. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Micellar extraction and high performance liquid chromatography-ultra violet determination of some explosives in water samples

An analytical method based on the cloud point extraction combined with high performance liquid chromatography is used for the extraction, separation and determination of four explosives; octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN). These compounds are extracted by using of Triton X-114 and cetyl-trimethyl ammonium bromide (CTAB). After extraction, the samples were analyzed using a HPLC-UV system. The parameters affecting extraction efficiency (such as Triton X-114 and CTAB concentrations, amount of Na₂SO₄, temperature, incubation and centrifuge times) were evaluated and optimized. Under the optimum conditions, the preconcentration factor was 40 and the improvement factors of 34, 29, 61 and 42 with detection limits of 0.09, 0.14, 0.08 and 0.40 (μg L⁻¹) were obtained for HMX, RDX, TNT and PETN, respectively. The proposed method was successfully applied to the determination of these compounds in water samples and showed recovery percentages of 97-102% with RSD values of 2.13-4.92%.     

含氟环形硅氧烷的立体异构和稳定性

文献曾报道, 1,3,5-三(3,3,3-三氟丙基)-1,3,5-三甲基环三硅氧烷(简称D^F~3)有两种立体异构体, 即顺式和反式。1,3,5,7-四(3,3,3-三氟丙基)-1,3,5,7-四硅氧烷(简称D^F~4)有四种异构体。但未报道其结构特点。本文试图进一步探讨D^F~3和D^F~4的立体异构体的结构和稳定性。     

Cascade Transformations of Trifluoromethanesulfonamide in Reaction with Formaldehyde

Trifluoromethanesulfonamide reacts with paraformaldehyde in acid medium to give both open-chain and cyclic condensation products: bis(trifluoromethylsulfonylamino)methane, N, N-bis(trifluoromethylsulfonylaminomethyl)trifluoromethanesulfonamide, 5-(trifluoromethylsulfonyl)dihydro-1,3,5-dioxazine, 3,5-bis(trifluoromethylsulfonyl)tetrahydro-1,3,5-oxadiazine, 1,3,5-tris(trifluoromethylsulfonyl)hexahydro-1,3,5-triazine, 5,7-bis(trifluoromethylsulfonyl)-1,3,5,7-dioxadiazocane, and 5,7,9-tris(trifluoromethylsulfonyl)-1,3,5,7,9-dioxatriazecane. Amidoalkylation of acetonitrile in the system trifluoromethanesulfonamide-paraformaldehyde-phosphoric acid leads to formation of N-(trifluoromethylsulfonylaminomethyl)acetamide.     

Low‐pressure barrier discharge ion source using air as a carrier gas and its application to the analysis of drugs and explosives

In this work, a low‐pressure air dielectric‐barrier discharge (DBD) ion source using a capillary with the inner diameter of 0.115 and 12 mm long applicable to miniaturized mass spectrometers was developed. The analytes, trinitrotoluene (TNT), 1,3,5‐trinitroperhydro‐1,3,5‐triazine (RDX), 1,3,5,7‐tetranitroperhydro‐1,3,5,7‐tetrazocine (HMX), pentaerythritol tetranitrate (PETN), nitroglycerine (NG), hexamethylene triperoxide diamine (HMTD), caffeine, cocaine and morphine, introduced through the capillary, were ionized by a low‐pressure air DBD. The ion source pressures were changed by using various sizes of the ion sampling orifice. The signal intensities of those analytes showed marked pressure dependence. TNT was detected with higher sensitivity at lower pressure but vice versa for other analytes. For all analytes, a marked signal enhancement was observed when a grounded cylindrical mesh electrode was installed in the DBD ion source. Among nine analytes, RDX, HMX, NG and PETN could be detected as cluster ions [analyte + NO₃]^? even at low pressure and high temperature up to 180 °C. The detection indicates that these cluster ions are stable enough to survive under present experimental conditions. The unexpectedly high stabilities of these cluster ions were verified by density functional theory calculation. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and Transformations of 1,3,5,7-Tetraazabicyclo[3.3.1]nonanes

Published data on the synthesis of 3,5-disubstituted 1,3,5,7-tetraazabicyclo[3.3.1]nonanes and their transformations into 1,3,5,7-tetraazacyclooctanes and 1,3,5-triazacyclohexanes are discussed.     

Thermal behavior and decomposition kinetics of Formex-bonded explosives containing different cyclic nitramines

Thermal behavior and decomposition kinetics of Formex-bonded PBXs based on some attractive cyclic nitramines, such as 1,3,5-trinitro-1,3,5-triazinane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). Actually, cis-1,3,4,6-tetranitrooctahy droimidazo-[4,5-d]imidazole (BCHMX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10, 12-hexaazaisowurtzitane (CL-20), was investigated by means of nonisothermal thermogravimetry (TG) and differential scanning calorimetry (DSC). It was found that the mass loss rate of PBXs involved in this research depends greatly on heating rate and the residue of the decomposition of these PBXs decreases with the heating rate. The onset of the exotherms was noticed at 215.4, 278.7, 231.2 and 233.7 °C with the peak maximum at 235.1, 279.0, 231.2 and 233.7 °C for RDX-Formex, HMX-Formex, CL-20-Formex, and BCHMX-Formex, respectively. Their corresponding exothermic changes were 1788, 1237, 691, and 1583 J g^?1. It was also observed that the dependence on the heating rate for onset temperatures of HMX- and BCHMX-based PBXs was almost the same due to their similar molecular structure. In addition, based on nonisothermal TG data, the kinetic parameters for thermal decomposition of these PBXs were calculated by isoconversional methods. It was shown that the Formex base has great effects on the activation energy distribution of nitramines. It was further found that the kinetic compensation effects occurred during the thermal decomposition of nitramine-based PBXs, and they almost have the same compensation effects due to similar decomposition mechanism.     

New theoretically predicted RDX‐ and β‐HMX‐based high‐energy‐density molecules

Theoretically new high‐energy‐density materials (HEDM) in which the hydrogens on RDX and β‐HMX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine and octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine, respectively) were sequentially replaced by (N NO₂)x functional groups were designed and evaluated using density functional theory calculations in combination with the Kamlet–Jacobs equations and an atoms‐in‐molecules (AIM) analysis. Improved detonation properties and reduced sensitivity compared to RDX and β‐HMX were predicted. Interestingly, the RDX and β‐HMX derivatives having one attached N NO₂ group [RDX‐(NNO₂)1 and HMX‐(NNO₂)1] showed excellent detonation properties (detonation velocities: 9.529 and 9.575 km·s⁻¹, and detonation pressures: 40.818 and 41.570 GPa, respectively), which were superior to the parent compounds. Sensitivity estimations obtained by calculating impact sensitivities and HOMO‐LUMO gaps indicated that RDX‐(NNO₂)1 and HMX‐(NNO₂)1 were less stable than RDX and HMX but more stable than any of the other derivatives. This method of sequential NNO₂ group attachment on conventional HEDMs offers a firm basis for further studies on the design of new explosives. Furthermore, the newly found structures may be promising candidates for better HEDMs.     

Synthesis of 1,3,5,7-tetraazacyclooctane derivatives

Tetraazaadamantane was converted under mild conditions into 1,3,5,7-tetraazabicyclo[3.3.1]nonane derivatives. The latter were transformed selectively into 1,3,5,7-tetraazacyclooctane derivatives avoiding the formation of 1,3,5-triazacyclohexane compounds.     

Ferrocenyl Ionic Compounds Containing [Fe(CN)6]3– Anions: Synthesis,Characterization, and Catalytic Effects during Combustion

Twenty‐eight novel ferrocenyl ionic compounds, composed of mononuclear 1‐ferrocenylmethylalkyldimethylammoniums, 1‐ferrocenylmethyl‐3‐alkylimidazoliums, or their dinuclear analogs and [Fe(CN)₆]^3– anion, were designed and synthesized to tackle significant volatility and migration tendency of ferrocene‐based burning rate catalysts (BRCs) used currently in the composite solid propellants. The new compounds were characterized by UV/Vis, FT‐IR, and elementary analysis. The crystal structures of compounds 2· 5H₂O and 3· CH₂Cl₂ · 4H₂O verified the successful preparation of the desired ionic compounds. The TG tests at 70 °C for 24 h revealed that the new compounds exhibit lower volatility than catocene. The cyclic‐voltammetry results suggested that new compounds are quasi‐reversible or irreversible redox systems. TheTG/DSC analyses exhibited that the compounds are of highly thermal stability. Their catalytic effects on the thermal degradation of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazacyclooctane (HMX) were investigated. The results showed that most of the compounds exert great effects on the thermal degradation of AP and RDX during combustion. 11 and 2 are comparable to catocene in the thermal decomposition of AP and RDX, respectively, and can therefore be used as alternatives of catocene in a composite solid propellant. Some new compounds are unexpectedly active in promoting the thermal disintegration of HMX.