Thermal Decomposition of HNIW and HNIW-Based Formulations

Pesce‐Rodriguez, Rose A.; Fifer, Robert A.; McNesby, Kevin L.; Morris, Jeffrey B.; Schroeder, Michael A.; Miser, Craig S.; Liebman, Shirley A.

doi:10.21236/ada255613

Cited by 4 publications

(7 citation statements)

References 5 publications

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“…The full list of the molecular ions obtained in Py-GC/MS of CL-20 is given in Table 1. These results obtained are in concurrences with those reported by Pesce-Rodriguez et al [17]. The first peak corresponds to unseparable low molecular weight gaseous species appeared within first 2 min.…”

Section: Resultssupporting

confidence: 93%

Studies on thermal decomposition mechanism of CL-20 by pyrolysis gas chromatography–mass spectrometry (Py-GC/MS)

Naik

Gore

Gandhe

et al. 2008

Journal of Hazardous Materials

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Section: Resultssupporting

confidence: 93%

Studies on thermal decomposition mechanism of CL-20 by pyrolysis gas chromatography–mass spectrometry (Py-GC/MS)

Naik

Gore

Gandhe

et al. 2008

Journal of Hazardous Materials

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“…Reported here are the theoretically predicted vibrational spectra of HNIW and its 2 H, 13 C, 15 N (all), 15 N (nitro), and 18 O isotopologues as well as the experimental Raman and FTIR/ ATR spectra of HNIW and 15 N nitro À HNIW. The calculated isotopic frequency shifts for HNIW and 15 N nitro À HNIW show good agreement with the experimental frequency shifts determined from Raman spectra, with a À NO 2 asymmetric stretching frequency shift of ~36.5 cm À 1 vs. 35.7 cm À 1 , re-spectively.…”

Section: Discussionmentioning

confidence: 99%

“…The vibrational frequencies and IR intensities were done by means of a Berry phase approach using the finite displacement method as implemented in CP2K [27,37]. The computed vibrational spectra of the HNIW isotopologues (substituted with 2 H, 15 N at all positions, 15 N on the nitro groups, 13 C, and 18 O) were performed in the same manner. As these are equilibrium zero-point energy calculations, it was assumed isotopic substitution would not affect the geometry.…”

Section: Methodsmentioning

confidence: 99%

“…The reported values are the nominal values given by the fits but are within the experimental resolution. The computed vibrational frequencies and IR intensities for the 2 H, 13 C, 15 N (all), 15 N (nitro), and 18 O HNIW isotopologues are given in Table S1; all computed frequencies are positive and represent intramolecular vibrations only. It is important to note that experimental spectra contain low frequency intermolecular vibrations which are not captured by theory.…”

Section: Figurementioning

confidence: 99%

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Vibrational Spectra of HNIW and its Isotopologues: A Combined Experimental and Computational Study

Burton

Steele

Crowhurst

et al. 2023

Propellants Explo Pyrotec

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Incorporating isotopically labelled materials in degradation experiments could help unravel the mechanism(s) of decomposition through use of the kinetic isotope effect. Characterizing synthesized isotopologues however requires an understanding of what observable signals are affected by the isotopic substitution. As vibrational spectroscopy can distinguish between isotopologues, it is an ideal characterization technique to evaluate isotopic variants. To this end, the vibrational spectra of HNIW and its deuterated ( 2 H), 13 C, 15 N (all), 15 N (nitro), and 18 O isotopologues have been computationally predicted in the gas phase using density functional theory. These results are compared to experimentally measured FTIR/ATR and Raman spectra of both unsubstituted HNIW and 15 N-labeled HNIW in which the six nitro groups were synthetically tagged with 15 N atoms ( 15 N nitro À HNIW). The experimental isotopic frequency shift for the À NO 2 asymmetric stretching frequencies agrees with that theoretically calculated (~35.7 cm À 1 vs. 36.5 cm À 1 , respectively). Furthermore, analysis of the theoretically predicted frequency shifts for all isotopologues suggest the À NO 2 bending modes are lower in frequency than previously reported. This assignment is supported by the experimentally measured isotopic shift of ~10.1 cm À 1 for these features (consistent with the predicted shift of ~13.1 cm À 1 ). This work expands our current understanding of the vibrational modes in HNIW as well as provides a method for future work on similar systems.

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“…There are several polymorphs (conformers) possible for CL-20 [11,14,[20][21][22][23][24][25][26]. To date five polymorphs have been isolated experimentally and four have been studied computationally.…”

Section: Conventional Ring Strain Energy (Crse) and Heat Of Formentioning

confidence: 99%

A Theoretical Investigation of the Ring Strain Energy, Destabilization Energy, and Heat of Formation of CL-20

Bumpus

2012

Advances in Physical Chemistry

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The cage compound CL-20 (a.k.a., 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, HNIW, or 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane) is a well-studied high-energy-density material (HEDM). The high positive gas- (ΔfHg°) and solid- (ΔfHs°) phase heat of formation values for CL-20 conformers have often been attributed to the strain energy of this cage compound and, by implication, to the conventional ring strain energy (CRSE) inherent in isowurtzitane which may be viewed as a “parent compound” (although not the synthetic precursor) of CL-20. ΔfHg° values and destabilization energies (DSEs), which include the contribution from CRSE, were determined by computation using a relatively new multilevel ab intio model chemistry. Compared to cubane, isowurtzitane does not have an exceptionally high CRSE. It is about the same as that of cyclopropane and cyclobutane. These investigations demonstrate that instead of the CRSE inherent in the isowurtzitane parent compound, the relatively high ΔfHg° and DSE values of CL-20 conformers must be due, primarily, to torsional strain (Pitzer strain), transannular strain (Prelog strain), and van der Waals interactions that occur due to the presence of the six >N–NO2 substituents that replace the six methylene (–CH2–) groups in the isowurtzitane parent compound. These conclusions are even more pronounced when 2,4,6,8,10,12-hexaazaisowurtzitane is viewed as the “parent compound.”

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Thermal Decomposition of HNIW and HNIW-Based Formulations

Cited by 4 publications

References 5 publications

Studies on thermal decomposition mechanism of CL-20 by pyrolysis gas chromatography–mass spectrometry (Py-GC/MS)

Studies on thermal decomposition mechanism of CL-20 by pyrolysis gas chromatography–mass spectrometry (Py-GC/MS)

Vibrational Spectra of HNIW and its Isotopologues: A Combined Experimental and Computational Study

A Theoretical Investigation of the Ring Strain Energy, Destabilization Energy, and Heat of Formation of CL-20

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