Melting Behavior and Heat of Fusion of Compounds that Undergo Simultaneous Melting and Decomposition: An investigation with HMX

Bhattacharia, Sanjoy K.; Weeks, Brandon L.; Chen, Chau‐Chyun

doi:10.1021/acs.jced.6b00769

Cited by 21 publications

(7 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For gallic acid, two thermochemical transitions were reported, namely a solid–solid and solid–liquid thermochemical transitions [ 15 ]. In addition, various explosives have melted during decomposition, e.g., HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) [ 16 ]. It is apparent that the vast majority of substances exhibiting a thermochemical transition are substances with the capability for increased hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

On the Thermodynamic Thermal Properties of Quercetin and Similar Pharmaceuticals

Tsioptsias

Tsivintzelis

2022

Molecules

View full text Add to dashboard Cite

The thermodynamic properties of pharmaceuticals are of major importance since they are involved in drug design, processing, optimization and modelling. In this study, a long-standing confusion regarding the thermodynamic properties of flavonoids and similar pharmaceuticals is recognized and clarified. As a case study, the thermal behavior of quercetin is examined with various techniques. It is shown that quercetin does not exhibit glass transition nor a melting point, but on the contrary, it does exhibit various thermochemical transitions (structural relaxation occurring simultaneously with decomposition). Inevitably, the physical meaning of the reported experimental values of the thermodynamic properties, such as the heat of fusion and heat capacity, are questioned. The discussion for this behavior is focused on the weakening of the chemical bonds. The interpretations along with the literature data suggest that the thermochemical transition might be exhibited by various flavonoids and other similar pharmaceuticals, and is related to the difficulty in the prediction/modelling of their melting point.

show abstract

Section: Introductionmentioning

confidence: 99%

On the Thermodynamic Thermal Properties of Quercetin and Similar Pharmaceuticals

Tsioptsias

Tsivintzelis

2022

Molecules

View full text Add to dashboard Cite

show abstract

“…Also, it has been proposed that the formation of liquid state during a reaction of initially solid substances may result in increased reaction rates [ 10 ]. The Bawn model has been used for organic explosives [ 25 ] that exhibit such an effect, e.g., octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine [ 26 ], and have been reported to exhibit simultaneous decomposition and melting. Interestingly, the concept of Bawn kinetics has also been applied to pharmaceuticals [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Thermochemical Transition in Low Molecular Weight Substances: The Example of the Silybin Flavonoid

et al. 2022

View full text Add to dashboard Cite

Silybin is a complex organic molecule with high bioactivity, extracted from the plant Silybum. As a pharmaceutical substance, silybin’s bioactivity has drawn considerable attention, while its other properties, e.g., thermodynamic properties and thermal stability, have been less studied. Silybin has been reported to exhibit a melting point, and values for its heat of fusion have been provided. In this work, differential scanning calorimetry, thermogravimetry including derivative thermogravimetry, infrared spectroscopy, and microscopy were used to provide evidence that silybin exhibits a thermochemical transition, i.e., softening occurring simultaneously with decomposition. Data from the available literature in combination with critical discussion of the results in a general framework suggest that thermochemical transition is a broad effect exhibited by various forms of matter (small molecules, macromolecules, natural, synthetic, organic, inorganic). The increased formation of hydrogen bonding contributes to this behavior through a dual influence: (a) inhibition of melting and (b) facilitation of decomposition due to weakening of chemical bonds.

show abstract

“…HMX is a rare compound that undergoes simultaneous melting and decomposition. Recent investigations of its melting properties with DSC by Bhattacharia et al 122 have revealed that at low heating rates of <5.5 °C/min, β-HMX does not melt but decomposes. At a 0.25 °C/min heating rate, the onset of decomposition is ∼237 °C, and at 6.0 °C/min, simultaneous decomposition and melting starts at ∼279 °C.…”

Section: Phase Transitions In Some Importantmentioning

confidence: 99%

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

2019

View full text Add to dashboard Cite

Under ambient conditions, energetic materials may exist in one or more than one metastable crystal structure. Under compression or when heated, the material may transform into a different structure or may decompose. Mapping the phase diagram of explosive materials at high pressures and temperatures is an important component to evaluate their performance and safety aspects. In particular, a detailed knowledge of polymorphism and the structural and chemical stabilities of the various phases is necessary to understand the reactive behavior of explosive materials in the high-pressure and high-temperature range that is relevant to shock-wave initiation. Phase transformations could be rate-dependent; that is, fast compression or rapid heating could result in different transformation pressures, temperatures, or even structures compared with static compression and slow heating because shock compression could be accompanied by sudden and extreme heating effects. Nevertheless, static methods are expected to give a fair idea of the structure of the materials under different P–T conditions and, from the structure, their performance characteristics. Also, the shock-wave physics and chemistry of explosives are so complex that in shock experiments it has not been possible to identify the intermediate phases of molecules during decomposition. Hence experiments with static high pressure and high temperature are necessary to gain insight into these processes. Additionally, computational modeling and simulations have been extensively used to understand the effects of pressure on explosives. There is considerable literature on these aspects of energetic materials accumulated over the years. We will review the current status of experimental results, primarily using X-ray diffraction, Raman, and infrared spectroscopies, as probes exploring the P–T phase diagram of important secondary explosives ammonium nitrate, TNT, TATB, PETN, RDX, HMX, CL-20, TEX, FOX-7, and TKX-50.

show abstract

Melting Behavior and Heat of Fusion of Compounds that Undergo Simultaneous Melting and Decomposition: An investigation with HMX

Cited by 21 publications

References 13 publications

On the Thermodynamic Thermal Properties of Quercetin and Similar Pharmaceuticals

On the Thermodynamic Thermal Properties of Quercetin and Similar Pharmaceuticals

Thermochemical Transition in Low Molecular Weight Substances: The Example of the Silybin Flavonoid

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

Contact Info

Product

Resources

About