Thermal Decomposition of Organic Peroxides TATP and HMTD by T‐Jump/FTIR Spectroscopy

The thermal decomposition of the peroxides, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) was investigated as a function of pressure, temperature and atmosphere by T‐jump/FT‐IR spectroscopy. In an Ar atmosphere at fast heating rates, the dominant decomposition product of TATP was methane rather than acetone which dominates at slow heating rates. The products of TATP were different in Ar and in air which implies that decomposition occurs primarily in the gas phase. In contrast, the products from HMTD were independent of the surrounding atmosphere implying that it decomposes primarily in the condensed phase. The IR spectra of the decomposition products of HMTD exhibited some dependence on pressure but not on the pyrolysis filament temperature.     

Determining the Vapor Pressures of Diacetone Diperoxide (DADP) and Hexamethylene Triperoxide Diamine (HMTD)

The vapor signature of diacetone diperoxide (DADP) and hexamethylene triperoxide diamine (HMTD) were examined by a gas chromatography (GC) headspace technique over the range of 15 to 55 °C. Parallel experiments were conducted to redetermine the vapor pressures of 2,4,6‐trinitrotoluene (TNT) and triacetone triperoxide (TATP). The TNT and TATP vapor pressures were in agreement with the previously reported results. Vapor pressure of DADP was determined to be 17.7 Pa at 25 °C, which is approximately 2.6 times higher than TATP at the same temperature. The Clapeyron equation, relating vapor pressure and temperature, was LnP (Pa)=35.9−9845.1/T (K) for DADP. Heat of sublimation, calculated from the slope of the line for the Clapeyron equation, was 81.9 kJ mole⁻¹. HMTD vapor pressure was not determined due to reduced thermal stability resulting in vapor phase decomposition products.     

Hexamethylenetetramine Dinitrate (HDN): The Precursor for RDX Production by Bachmann Process

Hexamethylenetetramine dinitrate (HDN) is a rather weak explosive but is used as a precursor for the synthesis of RDX, one of the most important secondary nitramine explosives. HDN has limited application because of its hygroscopic character. This paper reports on the synthesis and characterization of HDN in high yield and purity by the reaction of hexamine with nitric acid at temperatures below 15 °C. It was characterized by FTIR and ¹H NMR spectroscopy, Scanning Electron Microscopy (SEM) and Liquid Chromatography/Mass Spectrometry (LC/MS) measurements. The thermal characteristics of HDN were determined by DSC and TG/DTA. The DSC curve of HDN shows an endothermic peak at 170.5 °C corresponding to the melting point of HDN, followed by two exothermic peaks at 174.0 °C and 200.5 °C due to the decomposition. The differences in the thermal behavior of HDN samples, which were thermally aged at 50 °C, 100 °C, and 150 °C in a nitrogen atmosphere were examined. Additionally, some quantum chemical properties of the nitration of hexamethylenetetramine were calculated.     

Volatile compounds from thermally oxidized methyl oleate

Thermal oxidation of methyl oleate was studied over a range of temperatures from 50 C to 150 C for periods of time up to 30 min. Degradation was quantitatively followed by gas liquid chromatography (GLC) and liquid scintillation counting of the products of methyl oleate-U-¹⁴C heated under a stream of compressed air. Heptane, octane, 2-decanone, benzene,o-xylene, methyl hexanoate, methyl heptanoate and methyl octanoate were identified by GLC and mass spectrometry. Mass spectral evidence also was obtained for methyl pimelaldehydate, methyl suberaldehydate and methyl azelaaldehydate. Organic synthesis confirmed the identity of methyl azelaaldehydate. Most of the products formed suggested that autoxidation was responsible for the degradation occurring at the temperatures employed in this study. Paper No. 2628 from the Oregon Agricultural Experiment Station.     

Knudsen Effusion Measurement of Organic Peroxide Vapor Pressures

The vapor pressures of TATP over the temperature range 269.85–306.95 K and DADP over the temperature range 265.85–294.85 K were determined using a modified Knudsen effusion apparatus. The Clausius‐Clapeyron plot of log₁₀(p(Pa)) with 1/T provided a straight line for each material. This expression for TATP is log₁₀(p(Pa))=−(4497±80)/T(K)+(15.86±0.28) (error limits are 95 % confidence limits) and for DADP it is log₁₀(p(Pa))=−(4417±137)/T(K)+(16.31±0.48). These expressions yield values of the vapor pressure at 298.15 K of 6 Pa for TATP and 17 Pa for DADP, and heats of sublimation of 86.2±1.5 kJ mol⁻¹ for TATP and 84.6±2.6 kJ mol⁻¹ for DADP. Attempts were made to determine the vapor pressure of HMTD but it appears to have a vapor pressure too low for our system to reliably determine. A two month experiment did provide an upper limit estimate for the vapor pressure of HMTD of approximately 0.04 Pa at room temperature. Melting point and melting point range were used as verification of the identity and purity of the TATP and DADP used in these experiments, but this was not possible with HMTD since it detonates prior to melting.     

Polymerization and characterization of various di(pyridine)bis(trihalophenolato)cobalt(II) complexes in solid and melt states

The syntheses of distorted tetrahedral bis(pyridine)bis(trihalophenolato)cobalt(II) complexes from an aqueus solution were achieved and their characterization by FT‐IR, X‐ray, DSC, UV‐visible and elemental analysis in solid state or in melt form is reported. Polymerizations of these complexes were accomplished either at constant temperature, employing different time intervals or constant decomposition times while varying the temperature range. The slow decomposition at constant temperature leads to long chain products, whereas long chains formed at higher temperatures were during a constant time. The resulting poly(dihalophenylene oxide)s were characterized by FT‐IR, ¹H NMR, ¹³C NMR spectral analysis, differential scanning calorimetry and molecular weight determinations by viscometric method. © 2001 Society of Chemical Industry     

十溴二苯醚热解动力学及在聚苯乙烯中的热解行为

十溴二苯醚(decaBDE)是多种聚苯乙烯(PS)类塑料阻燃添加剂,其热解动力学对开发新型高效的电子塑料安全处置技术具有十分重要的意义,为此采用普适积分法成功关联了氮气中decaBDE的热解动力学参数。结果表明:固体decaBDE在306℃时熔融为液相并在400~450℃进一步汽化为气相,热重/红外(TG/IR)分析表明,其气相产物组成具有与decaBDE相同的红外特征;decaBDE热解过程可用三维扩散模型关联。进而通过对比分析decaBDE、PS和含decaBDE的阻燃PS样品的TG实验结果,发现阻燃塑料样品在热解时存在decaBDE与PS间的相互作用,表现为热解起始温度的降低和终止温度的升高。TG/IR分析表明:阻燃塑料样品的热解气相产物中不存在游离的HBr,decaBDE热解时产生的活性基团改变了PS的降解反应历程,使其气相产物具有与1,3-二苯基丁烷类似的红外特征。     

Water‐based non‐ionic polymeric surfactants as oil spill dispersants

In this paper, polyisobutylene succinic anhydride adduct (PIB‐SA) was modified by esterification with polyethylene glycol (PEG 600, 1000 and 2000) to obtain mono‐ and diterminal polyoxyalkynated PIB‐SA. The monoterminal products were reacted with pentamethylene‐hexamine (PMHA). The structures were confirmed by FT–IR and ¹H NMR analysis. The surface properties, interfacial tension and the effectiveness in oil dispersion of the synthesized polymeric surfactants are reported. The maximum efficiency of oil spill dispersants was reached when the surfactant molecule had two moities (polyoxyalkylene and polyamine units). © 1999 Society of Chemical Industry     

Recent developments in understanding the toxicity of PTFE thermal decomposition products

Fluropolymers, especially polytetrafluoroethylene (PTFE), have good fire-resistance properties, but their application is limited by concerns over the toxicity of their thermal decomposition products. In experiments using a tube furnace system similar to the DIN 53 436 method, the 30-minute (+ 14 days observation) LC₅₀ in mass loss terms was found to be 2.9 mgI^?1 (Standard Error 0.40) under non-flaming conditions, approximately ten times as toxic as wood and most other materials. Toxicity was due to upper respiratory tract and airway irritation, and was consistent with the known effects of carbonyl fluoride and hydrogen fluoride. When decomposed in the NBS cup furnace test under-non-flaming conditions, PTFE evolved extreme-toxicity products with an LC₅₀ of approximately 0.05 mgI^?1 (mass loss), approximately 1000 times as toxic as wood and most other materials. Toxicity was due to deep lung irritation and oedema. Investigations of the range of conditions under which the extreme toxicity of PTFE products occurs in both small-scale (200-litre) and intermediate-scale (6 m³) experiments have shown that the highest toxicity occurs when PTFE is decomposed under non-flaming conditions over a temperature range of 400–650°C, and when the primary decomposition products are subjected to continuous secondary heating. At higher or lower temperatures, when the sample is flaming, when decomposition products from wood are also present in the chamber, when secondary heating is curtailed, or when the molecule contains hydrogen as well as fluorine, the toxicity of the products is greatly reduced, tending towards the region of ten times the potency of most other materials. Extreme toxicity is associated with a particulate, but the particulate atmosphere is not always extremely toxic, the potency decreasing as the fumes age.     

Study on the Nitrolysis of Hexamethylenetetramine by NMR spectrometry

The nitrolysis of hexamethylenetetramine (hexamine, HA) and 1,3,5-trioxane was studied by NMR spectrometry. It was found that the structure of the nitrolysis products of the trioxane could be monomethylenedinitrate, dioxymethylenenitronitrate and trioxymethylenenitronitrate, O₂N(OCH₂)_nONO₂(n = 1,2,3). Comparison of the ¹H and ¹³C spectra of the nitrolysis mixture of HA with the nitrolysis products of trioxane proved that in the nitrolysis mixture of HA the methylene group which cannot be used to form 1,3,5-triazacyclohexane (hexogen, RDX)appears in compound (2) and not in compound (1).     

Study on the Nitrolysis of Hexamethylenetetramine by NMR spectrometry II. Some new evidences of the intermediate of HOCH2NHNO2 as a possible precursor to RDX

In this research, the RDX yield from nitrolysing hexamethylenetetramine (hexamine, HA) together with methylenedinitramine (MDNA) in 90% nitric acid was more than 100%. It was found that MDNA decomposed completely in 90% nitric acid, forming O(CH₂ONO₂)₂, while in HNO₃ NH₄NO₃ system the decomposed fragments of MDNA condensed into RDX. On the basis of the comparison of the experimental results to the ¹H-NMR spectra obtained by following the decomposition reaction of MDNA with nitric acid, the intermediate, HOCH₂NHNO₂, was postulated as one of the possible precursors to RDX both in Hale and in K process.     

Synthesis and antioxidant activity of some new thioglycoluril derivatives

ABSTRACT

A series of S-alkylated products was prepared by alkylation of thioglycoluril with various alkylation agents, i.e. ethyl bromide, ethylene dibromide and chloroacetic acid. The synthesis performed in DMF at 60°C using sodium hydroxide as a base to give the corresponding products with significant advantages such as high conversions, short reaction time, mild reaction conditions, and low cost, simple workup with moderate to excellent yields. The structures of the synthesized compounds have been deduced from their spectral (IR, ¹H-NMR and ¹³C-NMR) data. Significant antioxidant activity was observed for some members of the series.     

Aminotetryls: Synthesis,spectral characterization,thermal decomposition and explosive properties

This paper describes the synthesis and spectral investigations of two amino derivatives of N-methyl-N-(2,4,6-trinitrophenyl)nitramine (tetryl). Also discussed are the results from thermal decomposition studies on the three explosives, viz. tetryl, 3-aminotetryl (3 AT) and 3,5-diaminotetryl (3,5 DAT) and preliminary work on the explosive properties of the last two compounds. The aminotetryls have been prepared by the amination of the corresponding chlorotetryls. The yield was 87% for 3 AT, but was only 33% for 3,5 DAT, probably due to steric crowding around the benzene nucleus. The mass spectra show interesting differences in the electron impact fragmentation patterns of the three tetryls with the M⁺ ion relative intensities following the order 3,5 DAT > 3 AT > tetryl, which could be due to (a) resonance stabilization and (b) hydrogen bonding effects. Evidence for the latter is also found in the infrared spectra of these compounds. Arrhenius kinetic parameters derived from thermal decomposition studies of the three compounds are presented and show that 3,5 DAT is thermally less stable than 3 AT. Explosive sensitiveness tests indicate that the diamino compound is the most sensitive, the trend being 3,5 DAT > 3 AT > tetryl. This is contrary to the generally found desensitizing influence of NH₂ groups on the thermal stability and explosive sensitiveness of trinitroaromatic energetic molecules. Mechanisms to account for the observed thermal decomposition behaviour and explosive sensitiveness patterns are discussed.     

One-step synthesis of single-phase (Co,Mg, Ni,Cu, Zn) O High entropy oxide nanoparticles through SCS procedure: Thermodynamics and experimental evaluation

Evaluation of the thermodynamic aspects of the synthesis process offers a better insight through the single-step synthesis of high entropy oxide particles. The thermodynamic calculations were used to specify the required conditions (fuel type and fuel amount) for the synthesis of single-phase (Co, Mg, Ni, Cu, Zn) O particles. Moreover, the impact of the activities coefficients alteration on the formation of (Co, Mg, Ni, Cu, Zn) O single-phase was calculated. Experiments were carried out using glycine, urea, citric acid, and hexamine at various fuel to oxidizer ratios (φ = 1.05, 1, 0.95, and 0.9) to explore the effect of fuel type and φ values on physicochemical properties of final product. Obtained results indicated that single-phase (Co, Mg, Ni, Cu, Zn) O powders were synthesized using glycine at the fuel-lean condition. Prepared powders exhibited promising crystallinity (59%), the thermal stability of 400 °C, 28 nm particle size, high porosity, and 15 m². g^?1 surface area.     

Sensory irritation evoked by the thermal decomposition products of plasticized poly(vinyl chloride)

A decrease in respiratory rate in mice during exposure to irritating airborne chemicals has been utilized as a response parameter to characterize the degree of upper respiratory tract irritation (sensory irritation) to the thermal decomposition products of plasticized poly(vinyl chloride). The plasticized poly(vinyl chloride) was placed in a low mass vertical furnace and thermally decomposed in an air atmosphere at a programmed heating rate of 20°C min^?1. The thermogravimetric study of the plasticized poly(vinyl chloride) demonstrated that two distinct weight loss fractions occurred during the decomposition process. Groups of four male swiss-webster mice were exposed to the thermal decomposition products of the first weight loss fraction in the range 0.03–0.77 mg l^?1 and to the second weight loss fraction in the range 0.03–0.38 mg l^?1. Dose-response curves were plotted by utilizing the maximum percent decrease in respiratory rate during each exposure as the response parameter. Comparison of these curves to a dose-response curve for hydrogen chloride showed that both the first and second weight loss fraction of plasticized poly(vinyl chloride) were more potent than hydrogen chloride in terms of sensory irritation. From these dose-response relationships qualitative and quantitative predictions of human responses to the thermal decomposition products of plasticized.     

Characterization of Mg-substituted hydroxyapatite synthesized by wet chemical method

Mg-substituted hydroxyapatite made up of needle-like and plate-like particles containing different amounts of Mg (between 0.21 wt% and 2.11 wt%) were prepared via wet chemical precipitation method of a homogenous suspension of Mg(OH)₂/Ca(OH)₂ and an aqueous solution of H₃PO₄. According to the data of Brunauer–Emmett–Teller method and field emission scanning electron microscopy, high specific surface area Mg-substituted hydroxyapatite was obtained. Specific surface area of as-synthesized powders increased from 94.9 m² g⁻¹ to 104.3 m² g⁻¹ with increasing concentration of Mg up to 0.64 wt%. Fourier transform infrared spectroscopy, X-ray powder diffraction, differential thermal analysis, and heating microscopy, were used to evaluate thermal stability and sintering behavior of synthesis products. Increase in concentration of Mg in synthesis products (≥0.83 wt%) promoted decomposition of Mg-substituted hydroxyapatite to Mg-substituted β-tricalcium phosphate after thermal treatment.     

Preparation of magnesium hydroxide nanoplates using a bubbling setup

Magnesium hydroxide [MH] with hexagonal nanoplates were synthesized from lightly calcined magnesia (MgO), nitrogen fertilizer ((NH₄)₂SO₄) and alkaline air (NH₃), using a large bubbling setup designed by the authors. The effects of various reaction conditions, including the addition of surfactant, magnesium source, concentration of ions, and initial pH of reaction solution on the morphology, particle sizes, and dispersion properties of the synthesis products were investigated. XRD, SEM, laser particle size analyzer and TG-DTA have been employed to characterize these products. The experimental results showed that the regular-shaped MH products were about 2 μm in mean particle size (D50) and nanometers in thickness, and were loose enough for filtering. The diffraction intensity of the (001) direction was higher than that of the (101) direction. The Mg²⁺ conversion in the continuous setup reached 71% and the decomposition temperature of products was 404 °C.     

Fast pyrolysis of glucose‐based carbohydrates with added NaCl part 2: Validation and evaluation of the mechanistic model

A mechanistic model considering the significant catalytic effects of Na⁺ on fast pyrolysis of glucose‐based carbohydrates was developed in Part 1 of this study. A computational framework based on continuous distribution kinetics and mass action kinetics was constructed to solve the mechanistic model. Agreement between model yields of various pyrolysis products with experimental data from fast pyrolysis of glucose‐based carbohydrates dosed with NaCl ranging from 0–0.34 mmol/g at 500 °C validated the model and demonstrated the robustness and extendibility of the mechanistic model. The model was able to capture the yields of major and minor products as well as their trends across NaCl concentrations. Modeling results showed that Na⁺ accelerated the rate of decomposition and reduced the time for complete thermoconversion of carbohydrates. The sharp reduction in the yield of levoglucosan (LVG) from fast pyrolysis of cellulose in the presence of NaCl was mainly caused by reduced decomposition of cellulose chains via end‐chain initiation and depropagation due to Na⁺ favoring competing dehydration reactions. Analysis of the contributions of reaction pathways showed that the decomposition of LVG made a minor contribution to its yield reduction and contributed less than 0.5% to the final yield of glycolaldehyde from fast pyrolysis of glucose‐based carbohydrates in the presence of NaCl. © 2015 American Institute of Chemical Engineers AIChE J, 62: 778–791, 2016     

Solid state polymerization of bis(trichlorophenoxo) cobalt(ii) complex to give poly(dichlorophenylene oxide)

Synthesis of four-coordinated (tetrahedral) trichlorophenol cobalt(II) complex with neutral ligand pyridine was achieved from the aqueous solution and its characterization was performed by UV-visible, IR spectral and CHN analysis. Solid state thermal polymerization of the complex was accomplished first at constant temperature employing different time intervals and secondly at constant decomposition time. The poly(dichlorophenylene oxide)s so synthesized were characterized by IR, ¹H NMR and ¹³C NMR spectral analysis, T_g determination, as well as measurement of molecular weight by a viscometric method.     

Synthesis of civetone from palm oil products

Metathesis of ethyl oleate, catalyzed by WCl₆ and SnMe₄, provided diethyl 9-octadecenedioate (the desired starting material for the synthesis of civetone) in 99% yield. Dieckmann condensation of diethyl 9-octadecenedioate gave 2-ethoxycarbonyl-9-cycloheptadecenone (63% yield), the hydrolysis-decarboxylation reaction of which yielded civetone (93%). Identification of all products was by¹H nuclear magnetic resonance, infrared and mass spectroscopic data. This is the first report of the synthesis of civetone from palm oil-derived products.