1,3,4‐Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level

Abstract

Many energetic materials synthesized to date have limited applications because of low thermal and/or mechanical stability.T his limitation can be overcome by introducing structural modifications such as abridging group.Inthis study, as eries of 1,3,4-oxadiazole-bridged furazans was prepared. Their structures were confirmed by 1 Hand 13 CNMR, infrared, elemental, and X-ray crystallographic analyses.T he thermal stability,f riction sensitivity,i mpact sensitivity,d etonation velocity,and detonation pressure were evaluated. The hydroxylammonium salt 8 has an excellent detonation performance (D = 9101 ms À1 ,P = 37.9 GPa) and insensitive properties (IS = 17.4 J, FS = 330 N), which show its great potential as ah igh-performance insensitive explosive.U sing quantum computation and crystal structure analysis,t he effect of the introduction of the 1,3,4-oxadiazole moiety on molecular reactivity and the difference between the sensitivities and thermal stabilities of mono-and bis-1,3,4-oxadiazole bridges are considered. The synthetic method for introducing 1,3,4oxadiazole and the systematic study of 1,3,4-oxadiazolebridged compounds provide at heoretical basis for future energetics design.

Evolving the Scope of 5,5’‐Azobistetrazoles in the Search for High Performing Green Energetic Materials

“…In the field of energetic materials, the most common approaches for the synthesis of new molecules are the introduction of cage or ring strain, the oxidation of the carbon backbone, or a raise of the molecule's nitrogen content [1] . Widely used examples of merging these models are mainly 2,4,6‐trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), or hexanitrohexaaza‐isowurtzitane (CL‐20) [2–3] . However, since TNT in particular, as well as the decomposition products of RDX, turned out to be toxic, an intensive search for a substitute is underway [4–5] .…”

What Shall We Do with the Computed Detonation Performance? Comment on “1,3,4‐Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level”

“…Table 1s hows the results of the detonation velocity calculations for novel oxadiazoles synthesized by Shreeve et al [2] Clearly,the accuracyofreported [2] detonation velocity far exceeds the difference between the results of different methods,w hich reaches 0.7 km s À1 .I ndeed, opting for the values obtained with any other methodology than EXPLO5 (Table 1) may notably affected some of conclusions in the original study. [2] To see whether the problem is rather general, let us extend the list of considered compounds.F igure 1r epresents the detonation velocities obtained from the KJ empirical equa- [13] 1,2,9,10-tetranitrodipyrazolo[1,5d:5',1'-f][1,2,3,4]-tetrazine (TNDPT), [14] 3,3'-dinitroamino-4,4'-azoxyfurazan (DNAAF), [15] 1-methyl-3,4,5-trinitropyrazole (MTNP), 4,4'-dinitro-[3,3'-bi(1,2,5-oxadiazole)] 2,2'-dioxide (DNBF), [9,16] octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). Ad etailed discussion on the scatter of the V det values from Figure 1f alls beyond the scope of present contribution.…”

“…In the conclusion, Iw ould like to point out that some modern promising approaches to the calculations of detonation parameters appeared in the literature, [22,23] but the key [2] and calculated by various methods detonation velocity data.…”

1,3,4‐Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level

“…a) Molecular structure of 14•2H 2 O [51]. b) 2D layer-by layer stacking of 14•2 H 2 O. c) Hydrogen bonds between molecules in the same layer.…”