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Mechanism for Unimolecular Decomposition of HMX (1,3,5,7-Tetranitro-1,3,5,7-tetrazocine), an ab Initio Study

Chakraborty, Debashis and Muller, Richard P. and Dasgupta, Siddharth and Goddard, William A., III (2001) Mechanism for Unimolecular Decomposition of HMX (1,3,5,7-Tetranitro-1,3,5,7-tetrazocine), an ab Initio Study. Journal of Physical Chemistry A, 105 (8). pp. 1302-1314. ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20170519-142728041

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Abstract

To improve the mechanistic understanding of the possible decomposition in the gas phase of the energetic material HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), we used ab initio calculations to determine the various unimolecular decomposition channels. We find three distinct mechanisms:  (i) homolytic cleavage of N−N bond to form NO_2 (M = 46) and HMR (M = 250) which subsequently decomposes to form various products; (ii) successive HONO eliminations to give four HONO (M = 47) plus a stable intermediate (M = 108); (iii) O-migration from one of the NO_2 groups of HMX to neighboring C atom followed by the decomposition of intermediate (M = 296) to INT222 (a ring-opened RDX structure) and MN-oring (M = 74), which can undergo dissociation to smaller mass fragments. The decomposition scheme for HMX is similar to that for RDX presented earlier (J. Phys. Chem. A 2000, 104, 2261), except that concerted decomposition of HMX to four MN (M = 74) molecules is not a favorable decomposition pathway, whereas this pathway was found in RDX decomposition (both experimentally and theoretically). The formation of RDR-o in the N−N homolysis pathway 1 or the formation of INT222 in pathways 1 and 3 presents an unified mechanistic scheme for the decomposition of both of these nitramines. The HMX decomposition mechanism correlates with available condensed phase experimental results, but detailed comparison of the predicted gas phase energetics is not possible.


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URLURL TypeDescription
http://dx.doi.org/10.1021/jp0026181DOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp0026181PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/jp0026181PublisherSupporting Information
ORCID:
AuthorORCID
Dasgupta, Siddharth0000-0002-9161-7457
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2001 American Chemical Society. Received 24 July 2000. Published online 3 February 2001. Published in print 1 March 2001. This research was supported by the Caltech DoE -ASCI-ASAP project. The MSC facilities are also supported by grants from NSF CHE (95-12279), Chevron Corp., ARO-MURI, Beckman Institute, Exxon, Owens-Corning, Avery-Dennison, Dow Chemical, 3M, NIH, Asahi Chemical, BP Amoco, and ARO ASSERT.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
NSFCHE 95-12279
Chevron CorporationUNSPECIFIED
Army Research Office (ARO)UNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
ExxonUNSPECIFIED
Owens-CorningUNSPECIFIED
Avery-DennisonUNSPECIFIED
Dow ChemicalUNSPECIFIED
3MUNSPECIFIED
NIHUNSPECIFIED
Asahi ChemicalUNSPECIFIED
BP AmocoUNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:20170519-142728041
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170519-142728041
Official Citation:Mechanism for Unimolecular Decomposition of HMX (1,3,5,7-Tetranitro-1,3,5,7-tetrazocine), an ab Initio Study Debashis Chakraborty, Richard P. Muller, Siddharth Dasgupta, and William A. Goddard III The Journal of Physical Chemistry A 2001 105 (8), 1302-1314 DOI: 10.1021/jp0026181
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77610
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:19 May 2017 22:13
Last Modified:03 Oct 2019 17:59

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