Kinetic Stability and Propellant Performance of Green Energetic Materials

Rahm, Martin; Brinck, Tore

doi:10.1002/chem.201000413

Cited by 69 publications

(57 citation statements)

References 99 publications

(160 reference statements)

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“…[29] Solvation energies were obtained at the COSMO-B2PLYP [30] /aug-cc-pVTZ//PCM-B3LYP/6-31 + G(d) level using the ORCA [31] program. [19] The density of TNA was obtained from the volume of its 0.001 a.u. electron density contour using a B3LYP/6-31G(d) wavefunction and the HS95-v09 [32] program.…”

Section: Methodsmentioning

confidence: 99%

“…[16,19,22] A peak at À19 ppm (shift values refer to ADN solutions, shifts in KDN solutions are slightly different) was designated to N 2 O 4 , in excellent agreement with literature values. [23] This species is also expected to form, through decomposition of both N(NO 2 ) 2 À [16,19,22] and TNA (Scheme 1). In some cases, when extremely dry reagents were used, or when an excess of NO 2 BF 4 was added, an HNO 3 -N 2 O 5 equilibrium was observed between À40 and À55 ppm.…”

mentioning

confidence: 96%

“…The oxidation of N-(NO 2 ) 2 À requires a positive absolute potential of at least 4.4 eV. [19] (2)]. The procedure requires a strong nitration agent, which allows the nitronium cation (NO 2 + ) to be present in free form.…”

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confidence: 99%

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Experimental Detection of Trinitramide, N(NO₂)₃

et al. 2010

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There is an incentive for research directed towards new environmentally friendly oxidizers and energetic materials. [1][2][3] Recent examples for advances in polynitrogen chemistry are the bulk synthesis of the V-shaped N 5 + , [4,5] the tetrazole-based CN 7 , À[6] and the detection of cyclic N 5 À . [7,8] Compounds containing exclusively oxygen and nitrogen are desirable for applications such as environmentally benign rocket propulsion. Of those, the dinitramide anion (N-(NO 2 ) 2 À ) [9][10][11] is the heaviest compound known to date. Trinitramide (TNA; N(NO 2 ) 3 ) constitutes a possible energetic green oxidizer that could be suitable for future high-performance propellants. Only a few theoretical works have previously dealt with this hitherto unknown nitrogen oxide. [12][13][14] The heat of formation (DH 0 f(gas) ) of TNA has been estimated at between 38 and 71 kcal mol À1 , [12][13][14] and the N À N bond dissociation energy has been estimated to be 20-27 kcal mol À1 . [13,14] The existence of an N 4 O 6 intermediate has also been speculated to explain observed decomposition kinetics of dinitraminic acid (HN(NO 2 ) 2 ) in nitric acid.[15] To the best of our knowledge, no synthetic effort toward TNA has been attempted. Herein we present the first experimental detection of this exotic molecule.We initially subjected TNA to a thorough quantum chemical analysis. The aim of this study was to decipher the kinetic stability and different decomposition pathways in gas phase and in solution. We also performed calculations on two possible synthesis routes, and estimated physical properties such as density, heat of formation, vaporization, sublimation, and performance characteristics of TNA as a rocket-propellant component.Proposed self-decomposition pathways available to TNA are shown in Scheme 1. The NÀN bond dissociation enthalpy in the gas phase is calculated to be 28.2 kcal mol À1 . Owing to the favorable change in entropy, this dissociation is likely the dominant route for decomposition in the gas phase. The transition state TS1 (Scheme 1) was found to be in close competition with the homolytic bond fission, with a barrier corresponding to a relative free energy of 27.9 kcal mol À1 . Surprisingly, DFT methods, such as the widely used B3LYP, or the more recent B2PLYP functional, fail in describing the energy landscape of both these pathways. The barrier heights are underestimated by 8-11 kcal mol À1 compared to CBS-QB3 (extrapolated CCSD(T)) and SCS-MP2 calculations, which are in very good agreement. As we know from previous studies that B3LYP, B2PLYP, and highlevel ab initio methods (such as CCSD(T) and SCS-MP2) behave very similarly when treating N(NO 2 ) 2 À and its radical, [16] and, given the high accuracy of the latter methods, we can safely assume that the error by DFT stems from an overestimation of the TNA ground state energy. Thus, the limited interest in TNA might be caused by the wide use of B3LYP, which underestimates its stability.The character of TS1 is between a NO 2 radical and a NO 2 cation tran...

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Section: Methodsmentioning

confidence: 99%

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Experimental Detection of Trinitramide, N(NO₂)₃

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“…This transition could be used as an important fingerprint for identification of TNO by UV-Vis spectroscopy. Unfortunately, experimental studies [46], as well as our computational characterization [48], indicate that the excited state is dissociative and that irradiation at this wavelength region leads to photodissociation with NO, N 2 , and O − as the most probable products. Thus, salts of TNO are likely to be photosensitive, and this could become a serious drawback for their use in propellant compositions.…”

Section: Trinitrogen Dioxide Anionmentioning

confidence: 99%

“…This reaction is exothermic by 25 kcal/mol in THF [48]. The main difficulty will be the reduction of nitrous oxide and the inherent instability of N 2 O − towards dissociation into O − and N 2 .…”

Section: Trinitrogen Dioxide Anionmentioning

confidence: 99%

Theoretical Design of Green Energetic Materials: Predicting Stability, Detection, Synthesis and Performance

Brinck

Rahm

2014

Green Energetic Materials

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Kohn-Sham density functional theory (KS-DFT) is today the standard quantum chemical method for the optimization of molecular geometries and calculation of vibrational frequencies. It is generally used to probe potential energy surfaces and characterize transition states. The widely used B3LYP exchange-correlation functional has also been quite successful for energetic molecules and their reactions. In general, B3LYP geometries are more accurate than energies. However, there are examples of nitro-group rich systems where B3LYP produces both erroneous geometries and energies, and for some of these the more recent M06-2X functional [5] of Truhlar and coworkers performs considerably better. A general observation is that when the two functionals give geometries in consensus, these can be trusted for energy calculations at higher level. Double zeta basis sets augmented by Theoretical Design of Green Energetic Materials 17

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Nitrogen Catenation: Polyazoles and Polyazines

Politzer¹,

Murray²

2017

Patai's Chemistry of Functional Groups

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Polyazoles and polyazines are, respectively, five‐ and six‐membered nitrogen heterocycles. An interesting difference between their geometries is that it is possible in polyazoles (but not in polyazines) to distinguish between formal single and formal double bonds. Our particular focus in this chapter is on those polyazoles and polyazines that feature three or more linked nitrogens in their rings (nitrogen catenation). The presence of ring nitrogens is destabilizing, especially when they are linked. Several possible factors that may be responsible for this effect of catenation are discussed in detail, and it is emphasized that these factors are not mutually exclusive or independent of each other. The electrostatic potentials of the molecules of interest are analyzed and related to their relative stabilities. N‐oxide formation is one means of mitigating the destabilization caused by nitrogen catenation. The acidity/basicity of these polyazoles and polyazines is examined in terms of their electrostatic potentials and local ionization energies. Polyazoles and polyazines have been found to provide good molecular frameworks for energetic materials; this application is briefly mentioned.

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Kinetic Stability and Propellant Performance of Green Energetic Materials

Cited by 69 publications

References 99 publications

Experimental Detection of Trinitramide, N(NO₂)₃

Experimental Detection of Trinitramide, N(NO₂)₃

Theoretical Design of Green Energetic Materials: Predicting Stability, Detection, Synthesis and Performance

Nitrogen Catenation: Polyazoles and Polyazines

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Kinetic Stability and Propellant Performance of Green Energetic Materials

Cited by 69 publications

References 99 publications

Experimental Detection of Trinitramide, N(NO2)3

Experimental Detection of Trinitramide, N(NO2)3

Theoretical Design of Green Energetic Materials: Predicting Stability, Detection, Synthesis and Performance

Nitrogen Catenation: Polyazoles and Polyazines

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Experimental Detection of Trinitramide, N(NO₂)₃

Experimental Detection of Trinitramide, N(NO₂)₃