1.3.5.7- Tetranitro-l,3,5,7-tetraazacyclooctane

HMX (1,3,5, 7-tetranitro-l, 3,5,7-tetraazacyclooctane) is widely used as an ingredient in various explosives and propellants. A molecular solid at standard state, it has four known pol5miorphs, one of which, the 8 phase is comprised of six molecules per unit cell, as depicted in Fig. 10. We study the chemical decomposition of the dense fluid of this phase by conducting a high-density and temperature (p = 1.9 g/cm, T = 3500 K) quantum mechanical based molecular dynamics simulation. [50] To our knowledge, this is the first reported ab initio based/molecular dynamics study of an explosive material at extreme conditions for extended reaction times of up to 55 picoseconds, thus allowing the formation of stable product molecules. 

We have calculated the specific impulses of a large number of molecules using Eq. (1) in the manner described in the previous section. To facilitate comparisons, our values are given relative to that of HMX (I 1.3,5.7-tetranitro-l,3,5,7-tetraazacyclooctane). The results of some of these calculations are given in Tables I-III. Table I lists compounds with csdculated... 

Volume additivity methods generally do not take into account crystal packing efficiency or molecular conformation effects and thus will afford identical calculated densities for positional and conformational isomers and for compounds that possess different multiples of the same functional group composition. As an example, a volume additivity calculation predicts that 1,3,5- trini tro-1,3,5- triazacyclohex-ane (RDX), l,3,5,7-tetranitro-l,3,-5,7-tetraazacyclooctane (a-HMX), and ft-11M X all will possess the same crystal density, 1.783 g/cm3 [32]. In fact, the experimentally observed densities of these three compounds differ markedly (i.e., 1.806 [33], 1.839 [34], and 1.902 [35], respectively). 

The nitrolysis of hexamine is a direct route to the military high explosives 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and l,3,5,7-tetranitro-13,5,7-tetraazacyclooctane (HMX). " The direct nitrolysis of hexamine with dinitrogen pentoxide in absolute ifitric acid provides RDX in 57 % yield. RDX prepared by this process is exceptionally pure, but other reagents, like ammonium nitrate-nitric acid-acetic anhydride, give much higher yields, partly because they use ammonium nitrate to supplement for ammonium nitrogen deficiency in the reaction. 

Energetic secondary nitramines are currently a subject of increasing interest in high energy materials research [1-15]. This surely reflects the fact that two of the most effective (yet highly sensitive) military secondary explosives are nitramines, namely l,3,5-trinitro-l,3,5-triazacyclohexane (RDX, I) and l,3,5,7-tetranitro-l,3,5,7-tetraazacyclooctane (HMX, II)... 

Bulusu, S Weinstein, D.I., Autera, J.R., and Velicky, R.W., (1986), "Deuterium Kinetic Isotope Effect in the Thermal Decomposition of l,3,5-Trinitro-13 5-triazacyclohexane and 1,3,5,7-Tetranitro-1,3,5,7-tetraazacyclooctane Its Use as an Experimental Probe for Their Shock-Induced Chemistry", J. Phys. Chem., 90, pp. 4121 - 4126. 

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