Guangbin Cheng

A study of N-trinitroethyl-substituted aminofurazans: high detonation performance energetic compounds with good oxygen balance

Two energetic N-trinitroethyl-substituted aminofurazans 11 and 12, as well as nitramine 13 (the N-nitration product of 12) were synthesized. All the compounds were well characterized by NMR spectra, IR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Their structures were further confirmed by X-ray diffraction studies, which show favorable densities (1.82–1.87 g cm−3). Interestingly, they exhibit good thermal stability (Tdec = 159–230 °C), acceptable oxygen balance (−15.31%–0) and high positive heats of formation (268–1259.5 kJ mol−1). In addition, the performance calculations gave detonation pressures and velocities for the furazan derivatives in the range of 35.4–40.8 GPa and 8900–9486 m s−1, respectively. Furthermore, nitramine 13 (nitrate product of 12), having an oxygen balance of zero, exhibits outstanding detonation properties (ΔfHm, 1259.5 kJ mol−1; D, 9486 m s−1; P, 40.8 GPa), which could be used as a high detonation performance energetic material.

Synthesis and characterization of 1,1′-azobis(5-methyltetrazole)

A high-nitrogen compound (N10 structure), 1,1′-azobis(5-methyltetrazole) which is relatively stable, was obtained by azo coupling reactions with three different oxidants such as trichloroisocyanuric acid (TCICA), sodium dichloroisocyanurate (SDIC) and tert-butyl hypochlorite (t-BuOCl). In particular, TCICA has been used for the first time to oxidize N–NH2 to the N–NN–N linkage. The structural elucidation of the title compound was made by spectral and X-ray crystallographic analyses. The new N10 linkage containing compound exhibits both relative thermal stability and physical stability.

A Facile and Versatile Synthesis of Energetic Furazan‐Functionalized 5‐Nitroimino‐1,2,4‐Triazoles

An analogue-oriented synthetic route for the formulation of furazan-functionalized 5-nitroimino-1,2,4-triazoles has been explored. The process was found to be straightforward, high yielding, and highly efficient, and scalable. Nine compounds were synthesized and the physicochemical and energetic properties, including density, thermal stability, and sensitivity, were investigated, as well as the energetic performance (e.g., detonation velocities and detonation pressures) as evaluated by using EXPLO5 code. Among the new materials, compounds 4-6 and 11 possess high densities, acceptable sensitivities, and good detonation performances, and thereby demonstrate the potential applications as new secondary explosives.

New thermally stable energetic materials: synthesis and characterization of guanylhydrazone substituted furoxan energetic derivatives

New guanylhydrazone substituted furoxan energetic derivatives were synthesized via the condensation reactions of 3-methyl-4-furoxancarbaldehyde with aminoguanidine derivatives. The resulting compounds 1–5 were well characterized using IR spectroscopy, multinuclear NMR spectroscopy, differential scanning calorimetry, thermogravimetry analysis as well as elemental analysis. Additionally, the structures of compounds 1, 2 and 5 were confirmed by single crystal X-ray diffraction. Except for the compounds 1 and 2, all the remaining products exhibit good thermal stabilities with decomposition temperatures above 200 °C. The detonation pressure values calculated for these compounds range from 17.0 to 28.3 GPa, and the detonation velocities range from 6906 to 8210 m s−1. These values suggest that the guanylhydrazone substituted furoxan energetic derivatives could be potential candidates for thermally stable energetic materials.

A novel N–N bond cleavage in 1,5-diaminotetrazole: synthesis and characterization of 5-picrylamino-1,2,3,4-tetrazole (PAT)

The reaction of 1,5-diaminotetrazole with picryl chloride (PiCl) forms 5-picrylamino-1,2,3,4-tetrazole (PAT) rather than the expected 1-picrylamino-5-amino-1,2,3,4-tetrazole or 5-picrylamino-1-amino-1,2,3,4-tetrazole. The structure of PAT was confirmed by single-crystal X-ray diffraction. Some of the energetic properties of the synthesized compound were also studied.

N-Trinitroethyl-substituted azoxyfurazan: high detonation performance energetic materials

Azoxyfurazan derivatives based on the trinitroethyl functionality were synthesized. These energetic N-trinitroethyl-substituted azoxyfurazans were fully characterized by using 1H and 13C NMR spectroscopy, IR, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TG) as well as single crystal X-ray diffraction, and, in the case of N-trinitroethylamino azoxyfurazan 4, with 15N NMR spectroscopy. Furthermore, compound 4 and nitramine 5 have been tested for their responses to impact, friction, and electrostatic discharge. The detonation pressures and velocities of the azoxyfurazan derivatives were calculated, ranging from 35.8 GPa to 41.2 GPa and 8861 m s−1 to 9458 m s−1, respectively. Additionally, compound 5 having an oxygen balance of near zero (+2.5%), exhibits a favorable measured density (1.92 g cm−3) and excellent detonation property (ΔfHm, 962.1 kJ mol−1; P, 41.2 GPa; D, 9458 m s−1). Thus, these compounds could be potential high detonation performance energetic materials.

An efficient Au(I) catalyst for double hydroarylation of alkynes with heteroarenes

An efficient Ph3PAuCl/AgOTf-catalyzed double hydroarylation of alkynes with heteroarenes was developed. Functional alkynes undergo double addition with simple heteroarenes such as pyrroles, furans and thiophenes under mild reaction conditions. The corresponding double-adduct products with nearly 100% regioselectivities were obtained in moderate to high yields. The mechanism of the reaction is also discussed in this paper.

Compounds based on 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan as insensitive energetic materials

3-Amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan was synthesized by reacting 4-amino-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide with acetamide at a high temperature of 180 °C. N-Trinitroethylamino derivatives and energetic salts based on 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan, which is a combination of 1,2,5- and 1,2,4-oxadizaole rings, were synthesized and fully characterized by multinuclear NMR spectroscopy, IR, and elemental analysis. And, the structures of compounds 1, 3, 4, 7, 9 were further confirmed by single crystal X-ray diffraction. The thermal stabilities of 1–12 were determined by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), indicating that the reported compounds have moderate thermal stabilities (172–246 °C, except for 3 159 °C). Compounds 1, 4–12 are insensitive towards impact (≥40.1 J) and friction (≥360 N) which were measured by standardized impact and friction tests. Detonation performance was obtained based on the calculated heats of formation and measured densities which indicated that most of these materials are superior to TNT.

Energetic compounds featuring bi(1,3,4-oxadiazole): a new family of insensitive energetic materials

In this contribution, 5,5′-bis(trinitromethyl)-2,2′-bi(1,3,4-oxadiazole) (4) and 11 nitrogen-rich salts featuring bi(1,3,4-oxadiazole) were synthesised. Compound 4 was obtained by nitration of 2,2′-bi(1,3,4-oxadiazolyl)-5,5′-diacetic acid and the salts (6, 8–17) were prepared by facile deprotonation and metathesis reactions. All compounds were characterized by IR, multinuclear NMR spectroscopy and elemental analysis. The structures of 6, 9 and 15 were further confirmed by single crystal X-ray diffraction. The physicochemical as well as energetic properties of these compounds including density, thermal stability and sensitivity were investigated. Except for 12 and 15, most of the salts decompose at temperatures over 180 °C. The performance data from the calculated heats of formation and experimental densities indicate that many of the salts have potential applications as energetic materials. The tested sensitivities of these compounds illustrate that they are less sensitive than RDX towards impact, friction and electrostatic discharge.

Synthesis and characterization of a new family of energetic salts based on a guanidinium cation containing a picryl moiety

A new family of energetic salts based on a new guanidinium cation containing a picryl moiety, N-(2,4,6-trinitrobenzylideneamino)guanidinium cation, was synthesized and well characterized by IR and multinuclear NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and elemental analysis. The structures of N-(2,4,6-trinitrobenzylideneamino)guanidinium nitrate (1) and N-(2,4,6-trinitrobenzylideneamino)guanidinium 5-nitrotetrazolate (5) were confirmed by single crystal X-ray diffraction. Most of the salts decompose at temperatures over 180 °C. Furthermore, except for the salts 1 and 9, most energetic salts exhibit low impact sensitivities (20–40 J), friction sensitivities (220–340 N), and are insensitive to electrostatics. The detonation pressure values calculated for the energetic salts 1 and 3–9 range from 23.7 to 30.3 GPa, and their detonation velocities range from 7842 to 8394 m s−1. These values indicate that some energetic salts can be candidates for energetic materials that possess good thermal stability and low sensitivity.