Polyazido High‐Nitrogen Compounds: Hydrazo‐ and Azo‐1,3,5‐triazine

Abstract

The performance of a high explosive is measured by its detonation velocity (v D (km sec À1 )) and detonation pressure (P CJ (kbar)). These parameters are determined by the oxygen balance (OB CO ), [1a] density (1), and heat of formation (DH f ), [1b] the higher the oxygen balance, density, and heat of formation, the better the performance. The energy of traditional polynitro compounds (Scheme 1) is primarily derived from the combustion of the carbon backbone using the oxygen carried by the nitro group. [2] For modern polynitro compounds (Scheme 2), the performance is enhanced not only by an excellent oxygen balance but also by a ring/cage strain which improves both the heat of formation and density. [4] Recently, a new class of energetic compounds containing a large fraction of nitrogen has been investigated. [5][6][7][8] These "high-nitrogen" compounds form a unique class of energetic materials [5a, 9] whose energy is derived from their very high positive heat of formation rather than from the combustion of the carbon backbone or the ring/cage strain (Scheme 3). The high heat of formation is directly attributable to the large number of inherently energetic NÀN and CÀN bonds.High-nitrogen compounds containing polyazides possess even higher heats of formation because their energy content rapidly increases with the number of energetic azido groups in the molecule. However, they are notorious for their extreme sensitivity [10a] to spark, friction, and impact (H 50 ) [10b] as well as poor thermal stability, [10a, 11, 12] so their applications are very limited. Examples include 3,6-diazido-1,2,4,5-tetrazine [13] and cyanuric azide (2,4,6-triazido-1,3,5-triazine; [14] Scheme 4).

Preparation of Nitrogen‐Rich Nanolayered, Nanoclustered, and Nanodendritic Carbon Nitrides

“…TAAT was proposed as one of the intermediates in the decomposition of TAT, [12] and we recently developed a three-step synthetic pathway for this material. [18] Nitrogen-rich C 2 N 3 was prepared under a nitrogen atmosphere.[19] A 1.0 g crystalline sample of TAAT was loaded into a 50-mL stainless steel bomb, which was heated to 160 8C over 3 h and held at this temperature for an additional 4 h. The temperature was then increased to 185 8C over 5 h and maintained at this temperature overnight to yield glassy nanolayered C 2 N 3 carbon nitride with a density of 1.32 AE 0.01 g cm À3 . The glassy nanolayer was characterized by IR spectroscopy, gas pycnometry (GP), elemental analysis, thermogravimetric analysis (TGA), [20] and SEM imaging (Figure 1).…”

“…Slow release of the nitrogen gas over an extended period results in pockets interconnected by gossamer tunnels (Figure 1, right). From our previous study, [18] TAAT is a viscous material either at a temperature of 150 8C or when a trace of solvent remains in the sample. This plastic property makes TAAT the unique precursor for glassy nanolayered carbon nitride.…”

Green primary explosives: 5-Nitrotetrazolato- N 2 -ferrate hierarchies

“…The oxygen-rich NT Ϫ ligands contribute sensitivity and explosive energy to the coordination complex anions; thus, the green primaries with the greater number of NT Ϫ ligands are more sensitive and have better explosive performance (15). Explosive performance is determined by a combination of oxygen balance (OB CO ), density (), and heat of formation (⌬H f ).…”

“…Ring-strained nitro compounds (15) ; and octanitrocubane} have outstanding explosive performance and suitable sensitivity, but, unfortunately, they cannot be ligands, owing to the lack of appropriate atom donors (Fig. 3A) (15).…”

Theoretical study on novel nitrogen-rich energetic compounds of bis(amino)-azobis(azoles) with tetrazene unit

“…It was reported [48] that introducing the azo (−N0N−) linkage into nitrogen heterocyclics can not only improve their HOF but also their stability. In 2010, Li et al [49] synthesized 1,1′-azobis-1,2,3-triazole with a stable N8 chain by coupling two 1-amino-1,2,3-triazole molecules together, and investigated its thermal stability and photochromic properties.…”