New Thermal Decomposition Pathway for TATB

Delineating the chemical composition of TATB (1,3,5‐triamino‐2,4,6‐trinitrobenzene) residues produced from the exposure to abnormal thermal environments should lead to a better understanding of the decomposition paths. Identifying and quantifying each compound in thermally produced residues, monitors which compounds are degrading or forming along the decomposition route, as well as providing input for the kinetic models of those pathways.Here we report the methodology of isolating, identifying, and where possible, quantifying soluble compounds present in solid residues of thermally treated TATB (330 °C for tens of minutes). Samples were extracted with DMSO, separated using chromatography, and quantified using their absorption at 354 nm. Identification of unknown compounds was accomplished using high resolution mass spectrometry. TATB, F1 (diamino‐dinitro‐benzofurazan), HO‐TATB (2,4,6‐triamino‐1‐hydroxyl‐3,5‐dinitrobenzene), and T4A (1‐chloro‐3,5‐dinitro‐2,4,6‐triaminobenzene) were trace compounds detected in the unreacted TATB. Ten more compounds that formed in the residues were structurally identified including F2 (amino‐nitro‐difurazan). Several more compounds were observed but not completely identified. We propose possible structures for the unknowns. Of the compounds formed, F1 was the most abundant compound reaching 4.5 % by weight of the degraded solid sample. Other degradation compounds were estimated to sum to trace levels, well below 1 %. Most compounds were new, having not been detected and identified in previous studies of production grade and thermally aged TATB. Many compounds only reached detectable concentrations after several min of thermal exposure.

Section: Discussionsupporting

confidence: 51%

Section: Structure Of Compoundsmentioning

confidence: 93%

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Analysis of degradation products in thermally treated TATB

Coffee,

Panasci‐Nott,

Olivas

et al. 2023

“…At least as much mass is converted to an insoluble semi-char that first evolves and then quickly converts to a final char composition near the time of the first exotherm (Figure 11 bottom). The yield of gaseous products exceeds the soluble products at all extents of conversion (Figure 13), and early detection of both nitrogen and carbon oxides suggests that auto-oxidation is important at a very early stage [55], which might indicate that it is as fast or faster as the furazan formation above 250 °C and is possibly related to the insoluble reactive residue that persists up to 45 min.…”

Section: Interrupted Heating Dsc Experimentsmentioning

confidence: 99%

Towards a heat‐ and mass‐balanced kinetic model of TATB decomposition

Burnham,

Coffee,

Klunder

et al. 2023

TATB (1,3,5‐triamino‐2,4,6‐trinitrobenzene) was thermally degraded by two small‐scale analytical methods – simultaneous differential scanning calorimetry and thermogravimetric analysis (SDT) and a hot‐stage microscope with Fourier Transform Infrared (FTIR) analysis capabilities. SDT used ramped heating, isothermal soaking, and thermal pretreatment at various conditions. The heat flow and mass loss were monitored during various treatment conditions to derive chemical decomposition kinetics and Arrhenius parameters. FTIR experiments used isothermal heating, and changes were monitored spectroscopically. Solid samples generated at specific conditions were collected from both methods and were analyzed by DMSO extraction followed by chemical speciation by optical and mass spectrometric methods. Characterization provided the following reaction insights:1. TATB decreases in a sigmoidal pattern in isothermally heated samples. Other soluble products gradually increase in concentration and then abruptly decline in concentration during the second exotherm, such as diamino‐dinitro‐benzofurazan and amino‐nitro‐benzodifurazan.2. FTIR showed gradual changes in the amino and nitro functionality, shifting positions and decreasing intensity for the first 40 min. Then the solid gradually appeared more like an amorphous C with N incorporated, similar to previous studies on thermally degraded TATB‐type materials.3. Extracted residues (DMSO‐soluble components removed) examined by FTIR showed an abrupt change in chemical composition between 40‐ and 45‐min isothermal treatment, indicating early forming solids are different than later forming residues.4. A reliable mass‐ and energy‐balanced global reaction network must include at least two autocatalytic reactions, either in parallel or series, and at least one must have an explicit initiation reaction having a low activation energy.

“…Isotopic labeling in MS incrementally changes the mass (usually one/substitution), often moving analyte masses away from masses of common interferents and allows for easier monitoring of specific sites, particularly when low-molecularweight gases are produced. These high purity and substituted labeled compounds have been used in examining the thermal degradation process of TATB by all the spectroscopic techniques above [42][43][44].…”

Section: Spectroscopic Applications Of Isotopically Labeled Tatbmentioning

confidence: 99%

Syntheses and characterization of isotopically labeled 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB)**

Racoveanu,

Coffee,

Panasci‐Nott

et al. 2023

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Synthesis and characterization of chemical analogues of TATB, where specific atoms in the structure have been isotopically substituted, are reported. 15N, 2H, and 18O have replaced the naturally occurring isotope distributions in the amino and/or the nitro attendant sites and 13C has replaced the carbon in the ring structure. A modified wet‐amination method was used to produce the analogues, and the isotopic replacements were performed by selective choice of labeled precursors. Four 15N‐labeled compounds (N replaced in the amino and nitro positions), two deuterium‐labeled compounds (hydrogens replaced on the amino groups), and one 13C‐labeled compound (C in the ring substituted) were synthesized of high isotopic and chemical purity. One partially labeled 18O‐labeled compound (O in the nitro position) was a result of incomplete labeling due to exchange reactions during synthesis. The compounds were characterized by various spectroscopic methods – mass spectrometry (MS), solid‐state nuclear magnetic resonance (SS‐NMR), infrared (FTIR), powder x‐ray diffraction (PXRD), and differential scanning calorimetry (DSC), depending upon the substitution. These compounds have been critical to the efforts in understanding the decomposition pathways of TATB when exposed to abnormal thermal environments.