N-HMX

N-HMX. Code name for l-Nitroso-3,5,7-trinitro-1,3,5,7-tetra-azacyclooctane... 

Results, shown in Figure 13, on the decomposition of a HMX mixture, formed from equal amounts of I n-HMX and unlabelled HMX recrystallized from solution, show that the nitrogen atom in the NO group in ONTNTA originates from the parent HMX molecule. This precludes the addition of NO to the HMX radical as the major path to ONTNTA formation. 

Figure 13. The ion signals from m/z = 132 (/) to m/z =136 (0) that are formed in the mass spectrometer from the ONTNTA pyrolysis product. The ONTNTA products are formed during the decomposition of HMX fornied from a mixture of N-HMX and unlabelled HMX.

For this particular product, in addition to a decrease in analysis time, a non-destructive method is especially desirable because of other physical tests that are also required on each sample By FNAA, the total nitrogen content of a sample is first detd and then related to compn of the mixture. Since Octols contain no ingredients other than pure TNT (18.50% N) and pure HMX (37.84%), the following linear relationship is derived from the ealed nitrogen content of each ingredient ... 

The McGill workers postulated that, in their process, methylene nitramine (CH2=N—N02) is formed as an intermediate, which then tri-merizes to RDX. However, the existence of methylene nitramine has never been proven. Werner Bachmann (Ref 2) of the University of Michigan, during WWII, conceived of a combination process in which the Hale nitrolysis of Hexamine would occur first, and the remaining methylene would be converted to RDX by the Ross-Schiessler route. Using three feed streams Ac20, Hexamine In acetic acid, and AN in nitric acid, the Bachmann process results in an 80% yield of RDX (two moles from one of Hexamine), including a small amount of HMX. 

Measurements were made for HMX. The values shown are 3/4 of the corresponding product in Ref 4, since RDX is C 3Hg N 6 and HMX is C4H8N808. Highly confined samples Moles product/mole expl... 

Nitrite, N-nitrosamines and the explosives RDX and HMX yield reddish-violet j chromatogram zones on a pale pink-colored background. 

Lewis et al.106 calculated four possible decomposition pathways of the ot-HMX polymorph N-N02 bond dissociation, HONO elimination, C-N bond scission, and concerted ring fission. Based on energetics, it was determined that N-N02 dissociation was the initial mechanism of decomposition in the gas phase, whereas they proposed HONO elimination and C-N bond scission to be favorable in the condensed phase. The more recent study of Chakraborty et al.42 using density functional theory (DFT), reported detailed decomposition pathways of p-HMX, which is the stable polymorph at room temperature. It was concluded that consecutive HONO elimination (4 HONO) and subsequent decomposition into HCN, OH, and NO are the most energetically favorable pathways in the gas phase. The results also showed that the formation of CH20 and N20 could occur preferably from secondary decomposition of methylenenitramine. 

Investigated explosives included 2,4,6-trinitrotoluene (TNT), 2,4,6,N-tetranitro-N-methylaniline (tetryl), l,3,5-trinitro-l,3,5-triazacyclohexane (RDX), 1,3,5,7-tetranitro-l,3,5,7-tetrazacyclooctane (HMX) and pentaerythritol tetranitrate (PETN). The temperature of the injector, cooled with liquid CO2, was —5°C for 0.3 min, programmed from —5 to 250° C, at a rate of 200°C/min, with a final hold time of 8.4 min. The column temperature was 80° C for 2 min, programmed to 250° C at 25°C/min, with a final hold of 2 min. Electron ionization (El) in the positive-ion mode was used. Figure 4 shows the mass chromatograms of a mixture of explosives (lOppb each), extracted from water by Hquid—liquid extraction and X 100 concentration. Identification was based on typical fragment ions for each one of the explosives. 

The replacement of amine and amide hydrogen with a nitro group via direct nitration is an important route to A-nitro functionality. However, the cleavage of other bonds is also important. In the case of C-N bond cleavage the process is known as nitrolysis and is an invaluable route to many energetic materials (Section 5.6). The nitrolysis of hexamine and the syntheses of the important explosives HMX and RDX are discussed in Section 5.15. This area of chemistry could easily demand a separate chapter of its own and is the most complex and diverse in the field of nitramine chemistry. 

Nitrolysis is a term originally used for the rupture of a N-C bond leading to the formation of the N-NO2 group. A prime example is the nitrolysis of the N-CH2 bonds of hexamine to form the important military explosives RDX and HMX. Nitrolysis is the most important route available to polynitramine energetic materials. 

Kimura, J., and N. Kubota. 1980. Thermal decomposition process of HMX. Propellants Expolsives 5 1-8. 

Nitroguanidine (NQ) is a nitramine compound containing one N-NOj group in its molecular structure. In contrast to cyclic nitramines such as HMX and RDX, its density is low and its heat of explosion is also comparatively low. However, the Mg of its combustion products is low because of the high mass fraction of hydrogen contained within the molecule. Incorporating NQ particles into a double-base propellant forms a composite propellant termed a triple-base propellant, as used in guns. 

The oxidizer fragment (HNO3) of TAGN is attached by an ionic bond in the molecular structure and the physicochemical processes of TAGN combustion are different from those of HMX and RDX, the oxidizer fragment of which (-N-NO2) is attached by a covalent bond in their molecular structures. Though the flame temperature of TAGN is lower than that of HMX by 1200 K, the value of the thermodynamic parameter (Tf/M y appears to be approximately the same for both materials. The... 

Kubota, N., Physicochemical Processes of HMX Propellant Combustion, 19th Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, PA (1982), pp. 777-785. 

Shibamoto, H., and Kubota, N Super-Rate Burning of liF-Catalyzed HMX Py-rolants, 29th International Pyrotechnics Seminar, Westminster, Colorado, July 14-19th, 2002, pp. 147-155. 

Kubota, N Energetics of HMX-Based Composite-Modified Double-Base Propellant Combustion, J. of Propulsion and Power, Vol. 15, No. 6,1999, pp. 759-752. 

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