Spectroscopic Investigation of the Primary Reaction Intermediates in the Oxidation of Levitated Droplets of Energetic Ionic Liquids

Abstract

The production of the next generation of hypergolic, ionic-liquid-based fuels requires an understanding of the reaction mechanisms between the ionic liquid and oxidizer. We probed reactions between a levitated droplet of 1-methyl-4-amino-1,2,4-triazolium dicyanamide ([MAT][DCA]), with and without hydrogen-capped boron nanoparticles, and the nitrogen dioxide (NO) oxidizer. The apparatus exploits an ultrasonic levitator enclosed within a pressure-compatible process chamber equipped with complementary Raman, ultraviolet-visible, and Fourier-transform infrared (FTIR) spectroscopic probes. Vibrational modes were first assigned to the FTIR and Raman spectra of droplets levitated in argon. Spectra were subsequently collected for pure and boron-doped [MAT][DCA] exposed to nitrogen dioxide. By comparison with electronic structure calculations, some of the newly formed modes suggest that the N atom of the NO molecule bonds to a terminal N on the dicyanamide anion yielding [ON-NCNCN]. This represents the first spectroscopic evidence of a key reaction intermediate in the oxidation of levitated ionic liquid droplets.

The Role of the OH Group in Citric Acid in the Coordination with Fe3O4 Nanoparticles

“…In order to study the role of C–OH in CA molecules, pH is maintained at 10 to guarantee all COOHs and Fe–OH are deprotonated and leave the C–OH unchanged, while pH 3 guarantees all species protonated . By the combinative use of ATR-FTIR deuterium exchange, , spectral deconvolution, , and TGA/DTG analysis, the fine difference for the adsorption spectra of the CA with itinerary change in its initial concentration is quantitatively differentiated and analyzed. , The experimental results show that the OH group in CA, namely, C–OH, can only coordinate with iron species at pH 10, as shown in Scheme , ⑤–⑧, where the complex coordinated with both C–OH and COOH groups has been quantitatively confirmed for the first time, which is usually more stable than that formed by the COOH-only coordination at pH 3 such as ①–④ in Scheme . The conformational transformation among different coordinations can also be found as the iLtRS changes.…”

Effects of Nitrogen Dioxide on the Oxidation of Levitated exo-Tetrahydrodicyclopentadiene (JP-10) Droplets Doped with Aluminum Nanoparticles

“…The levitator experimental apparatus has been reviewed in detail previously , and employed in various experiments. ,,,− A schematic top view of the levitator apparatus illustrating its key components is presented in Figure . In the acoustic levitator, ultrasonic sound waves with a frequency of 58 kHz are produced by a piezoelectric transducer and reflect from a concave plate to generate a standing wave (see Figures –).…”

Greener synthetic approach for the preparation of substituted flexible dimeric pyridinium salts and its importance

“…Spectral investigation of the primary reaction intermediates in the oxidation of levitated droplets of energetic ionic liquid and their application [10]. Modular synthesis of γ‐valerolactone‐based ionic liquids and their application as alternative media for copper‐catalyzed Ullmann‐type coupling reactions and catalytic responses [11].…”