High Thermal Stability and Insensitive Fused Triazole-Triazine Trifluoromethyl-Containing Explosives (TFX)

Highly Promising Primary Explosive: A Metal-Free, Fluoro-Substituted Azo-Triazole with Unmatched Safety and Performance

A primary explosive is a perfect chemical compound for starting ignition in military and commercial uses. Over the past century, the quest for lead-free, environmentally friendly primary explosives has been a significant challenge and a long-standing goal. Here, an innovative organic primary explosive, (E)-1,2-bis(3-azido-5-(trifluoromethyl)-4H-1,2,4-triazol-4-yl)diazene (4), has been designed and synthesized through a straightforward three-step reaction from commercially available reagents. Importantly, this compound integrated two trifluoromethyl and azido groups into the N,N'-azo-1,2,4-triazole backbone to enhance the performance and safety. With this combination, it meets stringent criteria for safer, environmentally friendly primary explosives: being metal and perchlorate-free, possessing high density, excellent priming ability, and unique sensitivities to nonexplosive stimuli. It shows robust environmental resistance, good thermal stability, and effective detonation performance and also can be effectively initiated with a laser. Moreover, in the detonation test, compound 4 successfully detonated 500 mg of PETN with an ultralow minimum primer charge (MPC) of 40 mg, similar to traditional primary explosive LA (MPC: 40 mg) and outperforming organic metal-free primary explosives ICM-103 (MPC: 60 mg) and DDNP (MPC: 70 mg). The high detonation power, combined with its straightforward synthesis, cost-effectiveness, and easy large-scale manufacturing, makes it a superior alternative to currently used primary explosives such as lead azide (LA) and diazodinitrophenol (DDNP).

Employing the Trifluoromethyl Group on a 5/5 Fused Triazolo[4,3-b][1,2,4]triazole Backbone: A Viable Strategy for Attaining Balanced Energetics

In this study, we synthesized trifluoromethyl-substituted bis-triazole nitrogen-rich compounds (3-5) using a simple, cost-effective method. The newly made compounds were characterized using NMR, IR, elemental analysis, TGA-DSC, and single-crystal X-ray diffraction (for compounds 3 and 4). They demonstrated high density (1.82-1.92 g cm-3), moderate detonation performance (7567-7905 m s-1), good thermal stability (146-215 °C), and low sensitivity to impact (40 J) and friction (360 N), offering high potential nature as a cationic component in energetic salts, defense, and civilian applications.

Fluorine-Containing Functional Group-Based Energetic Materials

Molecules featuring fluorine-containing functional groups exhibit outstanding properties with high density, low sensitivity, excellent thermal stability, and good energetic performance due to the strong electron-withdrawing ability and high density of fluorine. Hence, they play a pivotal role in the field of energetic materials. In light of current theoretical and experimental reports, this review systematically focuses on three types of energetic materials possessing fluorine-containing functional groups F- and NF2 - substituted trinitromethyl groups (C(NO2 )2 F, C(NO2 )2 NF2 ), trifluoromethyl group (CF3 ), and difluoroamino and pentafluorosulfone groups (NF2 , SF5 ) and investigates the synthetic methods, physicochemical parameters, and energetic properties of each. The incorporation of fluorine-containing functional moieties is critical for the development of novel high energy density materials, and is rapidly being adopted in the design of energetic materials.

Thermal stability of azole-rich energetic compounds: their structure, density, enthalpy of formation and energetic properties

Energetic compounds, as a type of special material, are widely used in the fields of national defense, aerospace and exploration. Their research and production have received growing attention. Thermal stability is a crucial factor for the safety of energetic materials. Azole-rich energetic compounds have emerged as a research hotspot in recent years owing to their excellent properties. Due to the aromaticity of unsaturated azoles, many azole-rich energetic compounds have significant thermal stability, which is one of the properties that researchers focus on. This review presents a comprehensive summary of the physicochemical and energetic properties of various energetic materials, highlighting the relationship between thermal stability and the structural, physicochemical, and energetic properties of azole-rich energetic compounds. To improve the thermal stability of compounds, five aspects can be considered, including functional group modification, bridging, preparation of energetic salts, energetic metal-organic frameworks (EMOFs) and co-crystals. It was demonstrated that increasing the strength and number of hydrogen bonds of azoles and expanding the π-π stacking area are the key factors to improve thermal stability, which provides a valuable way to develop energetic materials with higher energy and thermal stability.

Regioselective Synthesis of 5-Trifluoromethyl 1,2,4-Triazoles via [3 + 2]-Cycloaddition of Nitrile Imines with CF3CN

We herein describe a general approach to 5-trifluoromethyl 1,2,4-triazoles via the [3 + 2]-cycloaddition of nitrile imines generated in situ from hydrazonyl chloride with CF₃CN, utilizing 2,2,2-trifluoroacetaldehyde O-(aryl)oxime as the precursor of trifluoroacetonitrile. Various functional groups, including alkyl-substituted hydrazonyl chloride, were tolerated during cycloaddition. Furthermore, the gram-scale synthesis and common downstream transformations proved the potential synthetic relevance of this developed methodology.

Functionalized Triazines and Tetrazines: Synthesis and Applications

The molecules possessing triazine and tetrazine moieties belong to a special class of heterocyclic compounds. Both triazines and tetrazines are building blocks and have provided a new dimension to the design of biologically important organic molecules. Several of their derivatives with fine-tuned electronic properties have been identified as multifunctional, adaptable, switchable, remarkably antifungal, anticancer, antiviral, antitumor, cardiotonic, anti-HIV, analgesic, anti-protozoal, etc. The objective of this review is to comprehensively describe the recent developments in synthesis, coordination properties, and various applications of triazine and tetrazine molecules. The rich literature demonstrates various synthetic routes for a variety of triazines and tetrazines through microwave-assisted, solid-phase, metal-based, [4+2] cycloaddition, and multicomponent one-pot reactions. Synthetic approaches contain linear, angular, and fused triazine and tetrazine heterocycles through a combinatorial method. Notably, the triazines and tetrazines undergo a variety of organic transformations, including electrophilic addition, coupling, nucleophilic displacement, and intramolecular cyclization. The mechanistic aspects of these heterocycles are discussed in a detailed way. The bioorthogonal application of these polyazines with various strained alkenes and alkynes provides a new prospect for investigations in chemical biology. This review systematically encapsulates the recent developments and challenges in the synthesis and possible potential applications of various triazine and tetrazine systems.

Regioselective synthesis of 3-trifluoromethyl 1,2,4-triazoles via photocycloaddition of sydnone with CF3CN

A photocycloaddition of sydnone with CF3CN for the regioselective synthesis of 3-trifluoromethyl 1,2,4-triazoles is reported.