Study on the Azido‐Tetrazolo Tautomerizations of 3,6‐Bis(azido)‐1,2,4,5‐tetrazine

Abstract

1IntroductionPolyazido heteroaromaticc ompounds have currently been extensively studieda sh igh-density energeticm aterials in material science [1][2].These compounds possess high density [3],h igh positive heat of formation [4][5][6],g ood thermal stability [7,8],a nd thermodynamicallyf avorable decomposition [9] that the mainc ombustion product is typically nitrogen gas [10],w hich result in numerous unique applications such as solid fuels in micropropulsion systems [11],s mokefree pyrotechnic fuels [12],g as generators, effective precursors for carbon nanospheres [13] and carbon nitride nanomaterials [14,15].The introduction of an azido group playsavery important role in increasing the heat of formation (HOF) of energetic compounds [16].H owever, most of described polyazides sucha s2 ,4,6-triazido-1,3,5-triazine( TAT)a nd 3,6-diazido-1,2,4,5-tetrazine( DIAT) are so sensitivet owards hock, spark, friction, and thermal impulse [17][18][19][20] that their applications are extremely limited. Despite there are no precise data comparing the sensitivity of an azide to its isomeric tetrazole, the aromatic tetrazoles are generally less sensitive toward shock and friction than covalent azides. Therefore, the isomeric tetrazoles formed by 1,3-dipolar cyclization [21] of the polyazides are potential replacements for the sensitive polyazides.Hiskey's grouph as made progresso ni mprovingt he sensitivity of polyazidoh eteroaromatic compounds [22].T he unexpected azido-cyclization and irreversible tetrazolo transformation of DIATd ifferentf rom other polyazidoh eteroaromatic compounds was reported. Equilibria of diazidotetrazine with its monotetrazole and one of the isomeric di-tetrazole were observeda td ifferent temperatures in DMSO. Unfortunately,n either the isomeric products could be distinguished or separated the 13 CNMR spectroscopic data sufficient to support the predictionf or the azido-cyclization product. Furthermore, until now,c ompared with thet heoretical studies [21,[23][24][25][26],t he experimental studies on the azido-cyclization of DIATare few,w hich may be due to the difficulty in characterization and danger arising from their extremely high sensitivity [27].We herein report further experiments and results on the azido-tetrazolo tautomerizationso fD IATw ith HPLC and 13 CNMR in three kinds of representative solvents according to their polarity,C HCl 3 ,C H 3 OH and DMSO, respectively.T he unexpectedi rreversible transformation resulted 6-aminotetrazolo[1,5-b]-1,2,4,5-tetrazine (ATTZ) as the final product, is disclosed. After at hrough survey of literature, we found that Licht and Ritter [28] had reported the preparation of ATTZ in 1994, but no other physical properties or crystal structures were available. In this paper,anovel and more efficient approach for the synthesis of ATTZ is developed and its crystal structure and physical properties are reported.Abstract:T he azido-tetrazolo tautomerizations of 3,6-diazido-1,2,4,5-tetrazine (DIAT) in different solvents were investigated with HPLC and 13 CNMR spect...

Properties and Promise of Catenated Nitrogen Systems As High-Energy-Density Materials

“…This product's crystal structure has been obtained. 535 The results of these studies 235,534,535 are summarized in Scheme 43.…”

“…In the case of the amine-azide, the biyclized product is isolable and may be trapped by oxidation of the teterazine ring to N -oxides ( 161 ). , In the case of the diazide, the tricyclized product is possible, but the bicyclized product is thermally unstable and decomposes at room temperature, releasing N 2 and forming the same isolable bicycle ( 160 ) as that formed from the amine-azide. This product’s crystal structure has been obtained . The results of these studies ,, are summarized in Scheme .…”

Transition-metal-mediated reduction and reversible double-cyclization of cyanuric triazide to an asymmetric bitetrazolate involving cleavage of the six-membered aromatic ring

“…This species can undergo a reversible isomerization to a indole-like fused bicycle containing a tetrazole ring fused to the six-membered azine. 3,7,[42][43][44][45][46] Oligomerized small molecules with high-nitrogen-carbon ratio are of interest in astrochemistry, where small molecules such as nitrogen and HCN in deep space may be activated by high energy radiation and aggregate into complex organic molecules. 47 Here we report a related double cycloaddition rearrangement reaction of cyanuric triazide (2,4,6-triazido-1,3,5triazine, 1) following reduction of the substrate to release N 2 , concomitant with the cleavage of the 6-membered ring to give N-([1,5 0 -bitetrazol]-5-yl)methanediiminate ligand in a dimeric metal complex.…”

An Unusual Layered Crystal Packing Gives Rise to a Superior Thermal Stability of Energetic Salt of 3,6‐Bishydrazino‐1,2,4,5‐tetrazine

“…Energetic materials include explosives, propellants, and pyrotechnics that are used for a variety of military purposes and civilian applications . Recently, nitrogen‐rich heterocycles are one of the high energy density materials (HEDMs) that each world power competed on, of which two important kinds are azoles and tetrazines . These high nitrogen content materials have a large number of N–N and C–N bonds and therefore exhibit large positive heats of formation.…”