Characterization of the Isothermal Compression Behavior of LLM-172

Abstract

The high-pressure behavior of 3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole (LLM-172) has been studied to 36 GPa by Raman spectroscopy and 50 GPa by X-ray diffraction. The Raman spectra and calculated unit-cell volumes at select pressures show reasonable qualitative agreement with first-principles density functional theory calculations. Raman peaks exhibit a gradual broadening and loss of intensity upon compression to near 20 GPa. Above 20 GPa, most Raman features disappear with the exception of modes associated with the skeletal ring modes. These modes were found to persist (although with low intensity) to 36 GPa. Because these modes exhibit very low compressibility over the pressure range studied, it is speculated that the ring structure is very stable. The X-ray diffraction suggests that while the crystal maintains an orthorhombic structure to near 40 GPa, it gradually undergoes a decomposition/amorphization beginning near 10 GPa. Analysis of the Raman results suggests that decomposition proceeds through isomerization, which leads to the formation of a C-O-N-O group rather than ring cleavage.

Thermodynamic, Raman Spectroscopic, and UV–Visible Optical Characterization of the Deltic, Squaric, and Croconic Cyclic Oxocarbon Acids

“…The computed values of combustion enthalpy at room temperature are Δ r c H °(H 2 C 4 O 4 (cr)) = −1261.70 kJ mol –1 and Δ r c H °(H 2 C 5 O 5 (cr)) = −1436.01 kJ mol –1 for the squaric and croconic acids, respectively. These values agree very well with the experimental values reported by Sellers (−1261.67 ± 0.33 kJ mol –1 ) and Ciezak-Jenkins et al , (−1436 kJ mol –1 ) for the squaric and croconic acids, respectively. The excellent agreement between these values gives strong support to the computed values of the thermodynamic properties of the cyclic oxocarbon acids reported in this article because the combustion enthalpies of organic compounds are generally determined experimentally with high accuracy.…”

“…The enthalpies of formation of the squaric and croconic acids at the standard state are known from experimental data. ,, The corresponding values are Δ f H °(H 2 C 4 O 4 (cr)) = −598.2 ± 0.4 kJ mol –1 and Δ f H °(H 2 C 5 O 5 (cr)) = −817.41 ± 1 kJ mol –1 . ,, It is important to note that the value reported by Sellers for squaric acid was unnoticed in the review works by Domalski et al − Using these values, the computed enthalpy and entropy functions of the squaric and croconic acids, the experimental thermodynamic properties of the corresponding elements from Chase et al, the enthalpies and Gibbs free energies of formation in terms of the elements were derived. The calculated values are given in Table .…”

“…Despite their importance, the majority of the thermodynamic properties of these materials and their temperature dependence are unknown. − In a subsequent step, the calculated thermodynamic properties of formation were used to evaluate the Gibbs free energies of reaction and associated reaction constants for the reactions of thermal decomposition of the squaric and croconic acids their reactions of complete combustion and the reaction of conversion between them in the presence of carbon monoxide as a function of temperature. The thermodynamic parameters of organic compounds are extraordinarily important not only in several scientific fields such as organic reactivity but also for many specific applications as the development of novel energetic materials. , Croconic acid, in particular, has been found to be useful for the next generation of gun propellants, which substantially increase the muzzle velocity. , The oxocarbon acids are very relevant materials in organic reactivity studies …”

High‐Pressure Characterization of Two Stereoisomers of Tetranitroester Cyclobutane

“…From the analysis of the P−V data, the following values for the bulk modulus ( B 0 ) and pressure derivative of ( B’ ) were derived: [cis‐trans‐cis] – B 0 =15.50±1.02 GPa and B’ =5.63±0.67, [all‐cis] – B 0 =11.65±0.26 GPa and B’ =6.22±0.18. These bulk modulus values are consistent with similar cyclic energetic molecules: BIDN (16.1±0.5/7.2), LLM‐105 (15±4/9±3), LLM‐172 (18.5±1.4/8.1), and DNDIF (14.9±0.9/6.7±0.6), respectively, for B 0 and B’ [7e, 8b–d]. The total volume compression upon increasing the pressure from ambient conditions to near 25.0 GPa was observed to be 32.9 % for [cis‐trans‐cis] and 38.9 % for [all‐cis].…”