Organic derivatives of hydroxylamine are important reagents in modern chemistry, but their thermal stability and related hazards have not yet been systematically studied. In the present study, we report a detailed thermal analysis of N-hydroxysuccinimide (NHS), N-hydroxyphthalimide (NHPI), 1,4-piperazine diol (PipzDiol), 1,3,5-trihydroxy-1,3,5-triazinan-1-ium chloride (formaldoxime trimer hydrochloride, TFO·HCl), and tris-oxime TRISOXH3. Then, we suggest the effective kinetic parameters and mechanisms of thermal decomposition. All these NOH-containing chemicals exhibit the exothermic decomposition when examined under conditions that retard material vaporization (such as DSC at elevated pressure or in hermetic crucibles). The application of Yoshida-type rules points to a certain hazard associated with TFO·HCl, TRISOXH3, and PipzDiol. Small-scale mechanical sensitivity testing validated the DSC-based hypothesis: TFO·HCl explodes at certain drop energies, and two other species decompose under impact. The standard drop energies corresponding to 50% probability of initiation are within 14–26 J. Overall, the reactive chemistry of the analyzed hydroxylamines may result in certain risks when they are stimulated by temperature or impact. Even for well-known reagents such as NHS, the amount of heat liberated in the course of decomposition is considerable (about 1300 J g–1). 1,3,5-Trihydroxy-1,3,5-triazinan-1-ium chloride by the amount of decomposition enthalpy (2200 ± 300 J g–1) and the level of the impact sensitivity (16 ± 5 J) can be compared with explosives, but it is less thermally stable, decomposing above 100 °C. The calculation of virtual detonation performance of this salt shows much higher stored energy as compared to other studied hydroxylamines. We propose the calculation of the detonation parameters for screened compounds as an alternative way of explosive hazard identification.

Novel energetic materials (EM) often combine two intrinsically counter trends, viz., a high energy density and mediocre safety parameters, like thermal stability and sensitivity toward mechanical stimuli. A rational design of promising EMs requires a proper understanding of their thermal stability at both macroscopic and molecular levels. In the present contribution, we studied in detail the thermal stability of 4,4’-dinitro-3,3’-diazenofuroxan (DDF), an ultrahigh-performance energetic material with a reliable experimental detonation velocity being very close to 10 km s-1. To this end, we employed a set of complementary thermoanalytical (DSC and TGA in the solid state along with advanced thermokinetic models, optical microscopy, and gas products detection) and theoretical techniques (DLPNO-CCSD(T) quantum chemical calculations). According to the DSC measurements, the solid-state thermolysis of DDF turned out to be a complex three-step process. The decomposition commences at ~85°C and the most intense heat release occurs at ~130°C depending on the heating rate. In order to proper describe the kinetics of DDF thermolysis beyond the simple Kissinger and Friedman methods, we applied a “top-down” kinetic approach resulting in the formal model comprised of three independent stages. A flexible Kolmogorov-Johnson-Mehl-Avrami-Erofeev equation was applied for the first decomposition stage along with the extended Prout-Tompkins equation for the second and third processes, respectively. The formal exponent in the former equation turned out to be close to a second order, thus suggesting a two-dimensional nuclei-growth model for the first stage. We rationalized this fact with the aid of optical microscopy experiments tracking the changes in the morphology of a solid DDF sample. Then, we complemented the formal macroscopic kinetics with some mechanistic patterns of the primary decomposition channels from quantum chemical calculations. The three reactions involving all important moieties of the DDF molecule turned out to compete very closely: viz., the nitro-nitrite isomerization, radical C(heterocycle)−N(bridge) bond scission and molecular decomposition comprised of the consequent N−O and C−C bond scissions in a furoxane ring. The DLPNO-CCSD(T) activation barriers of all these reactions were close to ~230 kJ mol-1. Most importantly, the calculations provide some mechanistic details missing in thermoanalytical experiment and formal kinetic models. Apart from this, we also determined a mutually consistent set of thermochemical and phase change data for DDF.

Mechanical stress is an important trigger of reactions in chemicals. Historically, the standard testing protocols for impact and friction sensitivity have been developed mainly for energetic materials and explosives. As a result, the structure− mechanical safety data is available for common explosives and is constantly reported for newly synthesized energetic compounds. The present work is motivated by the widely held among practitioners idea of high variability of mechanical sensitivity data, the advancements of new heterocyclic and high-nitrogen chemistry, and clear need in benchmark reference data set for QSPR modeling. We started from literature analysis and have already noted that many chemical papers lack the details required to replicate their findings regarding mechanical sensitivity. Next, we prepared over 100 species that have been previously synthesized and whose sensitivity had been reported by other researchers. The scatter within the literature and present study's results is illustrated and analyzed. Finally, we proposed a data set of 83 chemicals, which have the most reliable mechanical sensitivity data. This benchmark data set is recommended to be used for modeling of mechanical hazards of reactive chemicals. The logics of how this data set can be expanded in future is given; it might involve the collaborative efforts by different groups.

Energetic materials are important class of functional compounds that combine the beauty of extreme high-energy chemistry with rigorous constraints on safety and performance. As a result, the development of energetic materials is a challenging process that require the best of computational, chemical synthesis, and material design techniques. This review discusses the state-of-art of the energetics field, and then highlights the most recent synthetic advancements that go beyond – regioisomerism impact, almost all-nitrogen species, new mesoionic ring fragments, and compounds bearing elements other than traditional CHNO. The computational advancements are summarized further: the material genome approaches and high-throughput virtual screening. Next, the material science and crystal engineering design tools are reviewed, from cocrystal design and host-guest inclusion to various polymer coating techniques. Overall, we showcase the complexity of interdisciplinary problem of energetic materials design, that entraps the original mostly organic chemical field, but then material science and crystal engineering, and now targets the computational discovery and machine learning.