Effect of Ultraviolet Irradiation on Phase Transformations in HMX Polymorphs

Suryanarayana, B.; Autera, Joseph R.; Graybush, R J

doi:10.1080/15421406708083427

Cited by 21 publications

(35 citation statements)

References 3 publications

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“…HMX -> NO 2 + HCN + 3 H 2 C=N-NO 2 H 2 C=N-NO 2 -> NNO + H 2 CO In solution, the decomposition gases are predominately dinitrogen, and more nitrosamine is observed because the amine radical remaining after initial NO 2 loss is stabilized by the solvent, preventing further unraveling of the ring. This explains why previous labeling experiments with neat HMX 22,23 and RDX 24 showed no scrambling of label in the N 2 O, while we observed label scrambling in all the nitrogen-containing decomposition gases of DMN. In DMN decomposition, nitrous oxide is a minor product.…”

Section: Thermolysis Of Mixedsupporting

confidence: 45%

“…However, this result is in contrast to those observed when 15 NO 2 -labeled HMX was examined: all N 2 and N 2 O contained one labeled and one unlabeled nitrogen, and NO was exclusively 15 N labeled. 22 ) The composition of the gaseous decomposition products for all the examined nitramines is shown in Table III. RDX and HMX are unique among the nitramines studied in the large quantities of nitrous oxide produced.…”

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confidence: 99%

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Mechanisms of Nitramine Thermolysis

Oxley¹,

Kooh²,

Szekeres³

et al. 1994

J. Phys. Chem.

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The thermal decomposition of a number of nitramines was studied in dilute solution and in the melt.The nitramines included acyclic mononitramines [dimethylnitramine (DMN), diethylnitramine (DEN), dipropylnitramine (DPN), and diisopropylnitramine (DIPN)], cyclic mononitramines [N-nitro-piperidine (NPIP) and N-nitropyrrolidine (NPyr)], cyclic dinitramines [N-dinitropiperazine (pDNP), 1,3-dinitro-1,3-diazacyclopentane (DNI), and 1,3-dinitro-1,3-diazacyclohexane (mDNP)], and 1,3,5-trinitro-1,3,5-triazocyclohexane (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX), hexanitro-hexaazaisowurtzitane (HNIW), and 1,3,3-trinitroazetidine (TNAZ). For the acyclic and cyclic mono-and di-nitramines, the corresponding nitrosamines were the only or major condensed-phase product.Kinetics and activation parameters were determined for the thermolysis of dilute solutions (0.01 to 1.0 wt%) over range 200 o to 300 o C. The thermolyses were found to be first-order with the rate constants unaffected by use of deuterated solvent. As the nitramines became more complex than dimethylnitramine (DMN), the rate of decomposition increased and the product distribution became more complex. As the length of the aliphatic chain increased (DMN < DEN < DPN), the rate of thermolysis increased, yet nitrosamine remained the only observed condensed-phase product. When a secondary carbon was attached to the N-nitramine (DIPN) rather than primary (DPN), the rate of decomposition increased and a new condensed-phase product was observed. Among the cyclic nitramines, the rate of decomposition increased as the number ofNNO 2 groups increased (NPIP < pDNP; NPyr < DNI; mDMP < RDX). The position of the nitramine groups affected the decomposition; meta NNO 2 groups (mDNP) decomposed faster than para (pDNP). Ring strain decreased stability: mDNP < DNI; HMX < RDX. In complex nitramines, the increase in decomposition rate, the appearance of new products, and the change in the relative importance of nitrosamine and of N 2 and N 2 O is attributed to new decomposition routes available to them. However, since complex nitramines (e.g. RDX) maintain first-order kinetics and since most have activation energies in the range of 40 to 50 kcal/mol, it is believed that the triggering mechanism remains N-NO 2 homolysis. Intramolecular hydrogen transfer is also considered an important mode of nitramine decomposition. IntroductionBefore attempting to understand the mechanisms operating in species containing multiple nitramine functionalities, we examined the simple nitramine, dimethylnitramine (DMN).

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Section: Thermolysis Of Mixedsupporting

confidence: 45%

mentioning

confidence: 99%

Mechanisms of Nitramine Thermolysis

Oxley¹,

Kooh²,

Szekeres³

et al. 1994

J. Phys. Chem.

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“…15 N-tracer studies (6) indicated that N±N bonds are preserved during the formation of N 2 O; thus, one may assume that transfer of an oxygen atom to the CH 2 group and breaking of the C±N bond is an important step in the decomposition according to Robertson. However, since the total nitrogen was not accounted for in these experiments, the breakage of a N±N bond may not be ruled out as the initial step in the decomposition.…”

Section: Computer Modeling Experimental Data Results and Discussionmentioning

confidence: 98%

Computer Modeling of Probable Decomposition Reactions: Cyclonitramines

Pivina

Sokerina

Lushnikov

et al. 1999

Propellants, Explosives, Pyrotechnics

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SummaryAn approach to computer synthesis and retrosynthesis of organic compounds was formulated, and the CASB (Computer-Assisted Structure Building) software for its computer implementation was created. The approach was evaluated by the example of computer generation of probable routes for reactions of homolytic decomposition. Elementary steps of homolysis reactions were modeled with the use of the``retrosynthetic'' method. Each elementary reaction describes fragments that should be present in the structure and structural modi®cations that should be carried out to obtain reaction products. Target fragments are described in terms of production rules by specifying types of atoms, their formal charges and radical states, numbers of adjacent heteroatoms, hybridizations, etc. All possible intermediates of molecular homolysis reactions are generated by the program in a single step and then used in further search for probable pathways of decomposition during subsequent steps until the given maximum number of steps is achieved. Screening of advantageous pathways for these reactions was based on a set of empirical rules. The results obtained by the suggested approach and the corresponding program were illustrated by the example of some cyclic nitramines (RDX and HMX) and demonstrated good agreement with the experiment.

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“…< 1000 K, well below detonation temperature) of the decomposition products of condensedphase HMX. 45,71 These studies tend to identify final gas products (such as H 2 O, N 2 , H 2 , CO, CO 2 , etc.) from the surface burn, and the authors aspire to establish a global decomposition mechanism.…”

Section: First Principles Simulations Of High Explosivesmentioning

confidence: 99%

The Reactivity of Energetic Materials at Extreme Conditions

Fried¹

2007

Reviews in Computational Chemistry

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Effect of Ultraviolet Irradiation on Phase Transformations in HMX Polymorphs

Cited by 21 publications

References 3 publications

Mechanisms of Nitramine Thermolysis

Mechanisms of Nitramine Thermolysis

Computer Modeling of Probable Decomposition Reactions: Cyclonitramines

The Reactivity of Energetic Materials at Extreme Conditions

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