Comparative Theoretical Studies on a Series of Novel Energetic Salts Composed of 4,8-Dihydrodifurazano[3,4-b,e]pyrazine-based Anions and Ammonium-based Cations.

Binghui Duan,Xianming Lu,Ning Liu,Hongchang Mo,Bozhou Wang

doi:10.3390/molecules24183213

Abstract

4,8-Dihydrodifurazano[3,4-b,e]pyrazine (DFP) is one kind of parent compound for the synthesis of various promising difurazanopyrazine derivatives. In this paper, eleven series of energetic salts composed of 4,8-dihydrodifurazano[3,4-b,e]pyrazine-based anions and ammonium-based cations were designed. Their densities, heats of formation, energetic properties, impact sensitivity, and thermodynamics of formation were studied and compared based on density functional theory and volume-based thermodynamics method. Results show that ammonium and hydroxylammonium salts exhibit higher densities and more excellent detonation performance than guanidinium and triaminoguanidinium salts. Therein, the substitution with electron-withdrawing groups (–NO2, –CH2NF2, –CH2ONO2, –C(NO2)3, –CH2N3) contributes to enhancing the densities, heats of formation, and detonation properties of the title salts, and the substitution of –C(NO2)3 features the best performance. Incorporating N–O oxidation bond to difurazano[3,4-b,e]pyrazine anion gives a rise to the detonation performance of the title salts, while increasing their impact sensitivity meanwhile. Importantly, triaminoguanidinium 4,8-dihydrodifurazano[3,4-b,e]pyrazine (J4) has been successfully synthesized. The experimentally determined density and H50 value of J4 are 1.602 g/cm3 and higher than 112 cm, which are consistent with theoretical values, supporting the reliability of calculation methods. J4 proves to be a thermally stable and energetic explosive with decomposition peak temperature of 216.7 °C, detonation velocity 7732 m/s, and detonation pressure 25.42 GPa, respectively. These results confirm that the derivative work in furazanopyrazine compounds is an effective strategy to design and screen out potential candidates for high-performance energetic salts.

Highlights

Very recently, there has been a growing interest in the development of nitrogen-rich heterocycle energetic compounds (NHEC)
According to Kamlet–Jacobs equation [31], the detonation velocity and pressure of an energetic compound are proportional to its density and a high density coming up with more energy packed compound are proportional to its density and a high density coming up with more energy packed in in per unit volume is desirable
–C(NO2 )3 substituents are helpful for increasing the densities of 4,8-dihydrodifurazano[3,4-b,e]

Summary

Introduction

There has been a growing interest in the development of nitrogen-rich heterocycle energetic compounds (NHEC). These high nitrogen energetic materials feature attractive characteristics including high density, insensitivity to external stimuli, and environmentally benign decomposition products, which make them prospective and promising candidates for smokeless propellants, gas generators, and novel low-sensitivity high-energy explosives [1,2,3,4]. Energetic nitrogen-rich ionic salts are classified as high nitrogen energetic materials. These salts behave superior to atomically similar nonionic compounds in that they often possess negligible vapor pressures, lower melting points, higher densities, and better cohesive energy densities, which provide the best agreement between. There is a big π-conjugated molecular system in furazanopyrazine anions, resulting in thermally stable and insensitive ionic salts

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Conclusion