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First Principles Study of the Ignition Mechanism for Hypergolic Bipropellants: N,N,N′,N′-Tetramethylethylenediamine (TMEDA) and N,N,N′,N′-Tetramethylmethylenediamine (TMMDA) with Nitric Acid

Liu, Wei-Guang and Dasgupta, Siddharth and Zybin, Sergey V. and Goddard, William A., III (2011) First Principles Study of the Ignition Mechanism for Hypergolic Bipropellants: N,N,N′,N′-Tetramethylethylenediamine (TMEDA) and N,N,N′,N′-Tetramethylmethylenediamine (TMMDA) with Nitric Acid. Journal of Physical Chemistry A, 115 (20). pp. 5221-5229. ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20110608-072523213

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Abstract

We report quantum mechanics calculations (B3LYP flavor of density functional theory) to determine the chemical reaction mechanism underlying the hypergolic reaction of pure HNO_3 with N,N,N′,N′-tetramethylethylenediamine (TMEDA) and N,N,N′,N′-tetramethylmethylenediamine (TMMDA). TMEDA and TMMDA are dimethyl amines linked by two CH_2 groups or one CH_2 group, respectively, but ignite very differently with HNO_3. We explain this dramatic difference in terms of the role that N lone-pair electrons play in activating adjacent chemical bonds. We identify two key atomistic level factors that affect the ignition delay: (1) The exothermicity for formation of the dinitrate salt from TMEDA or TMMDA. With only a single CH_2 group between basic amines, the diprotonation of TMMDA results in much stronger electrostatic repulsion, reducing the heat of dinitrate salt formation by 6.3 kcal/mol. (2) The reaction of NO_2 with TMEDA or TMMDA, which is the step that releases the heat and reactive species required to propagate the reaction. Two factors of TMEDA promote the kinetics by providing routes with low barriers to oxidize the C: (a) formation of a stable intermediate with a C–C double bond and (b) the lower bond energy for breaking the C–C single bond (by 18 kcal/mol comparing to alkane) between two amines. Both factors would decrease the ignition delay for TMEDA versus TMMDA. The same factors also explain the shorter ignition delay of 1,4-dimethylpiperazine (DMPipZ) versus 1,3,5-trimethylhexahydro-1,3,5-triazine (TMTZ). These results indicate that TMEDA and DMPipZ are excellent green replacements for hydrazines as the fuel in bipropellants.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp202021sDOIUNSPECIFIED
http://pubs.acs.org/doi/abs/10.1021/jp202021sPublisherUNSPECIFIED
ORCID:
AuthorORCID
Liu, Wei-Guang0000-0002-6633-7795
Dasgupta, Siddharth0000-0002-9161-7457
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2011 American Chemical Society. Received: March 02, 2011 Revised: April 13, 2011. Publication Date (Web): April 28, 2011. We thank Prof. Stefan T. Thynell, Prof. Rich Yetter, and Dr. Shiqing Wang for helpful discussions. This research was supported by an ARO-MURI grant (W911NF-08-1-0124, Ralph Anthenien). The computational facility was funded by DURIP grants from ARO and ONR.
Funders:
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-08-1-0124
Office of Naval Research (ONR)UNSPECIFIED
Issue or Number:20
Record Number:CaltechAUTHORS:20110608-072523213
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110608-072523213
Official Citation:First Principles Study of the Ignition Mechanism for Hypergolic Bipropellants: N,N,N′,N′-Tetramethylethylenediamine (TMEDA) and N,N,N′,N′-Tetramethylmethylenediamine (TMMDA) with Nitric Acid Wei-Guang Liu, Siddharth Dasgupta, Sergey V. Zybin, and William A. Goddard, III pp 5221–5229 Publication Date (Web): April 28, 2011 (Article) DOI: 10.1021/jp202021s
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23937
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:08 Jun 2011 14:51
Last Modified:03 Oct 2019 02:51

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