Asymmetric Carbamate Derivatives Containing Secondary Nitramine, 2,2,2‐Trinitroethyl, and 2‐Fluoro‐2,2‐dinitroethyl Moieties

Abstract

In this work, the syntheses of 2,2,2‐trinitroethyl‐(2‐nitro‐2‐azapropyl)carbamate (5), its analogue 2‐fluoro‐2,2‐dinitroethyl(2‐nitro‐2‐azapropyl)carbamate (6), and the corresponding 2,2,2‐trinitroethyl(2‐nitro‐2‐azapropyl)nitrocarbamate (7) and 2‐fluoro‐2,2‐dinitroethyl(2‐nitro‐2‐azapropyl)nitrocarbamate (8) are presented. The compounds were characterized thoroughly by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, differential scanning calorimetry measurements and single‐crystal X‐ray diffraction. In addition, the hitherto unknown low‐temperature crystal structures of the starting materials 2‐nitro‐2‐azapropyl chloride (1) and 2‐nitro‐2‐azapropyl isocyanate (2) are presented. Owing to the positive oxygen balance of the carbamate derivatives, their suitability as potential oxidizers in energetic formulations with aluminium as the fuel is investigated and discussed. Standard enthalpies of formation were calculated at the CBS‐4M level of theory. With these values and the experimental densities from room‐temperature pycnometer measurements, several detonation parameters, such as the detonation pressures and velocities of the crude materials as well as the specific impulses of their formulations with aluminium, were computed by using the EXPLO5 (V6.01) computer program and compared with those of the corresponding mixtures with ammonium perchlorate as the oxidizer. Furthermore, the sensitivities towards impact, friction and electrostatic discharge were determined by using the BAM drop‐hammer and friction tester as well as a small‐scale electrical discharge device.

Contributions to the Chemistry ofN‐Methylnitramine: Crystal Structure, Synthesis of Nitrogen‐Rich Salts, and Reactions towards 2‐Nitro‐2‐azapropyl Derivatives

“…Owing to the ability of rotation of the NO 2 group and the lower π character of the elongated N–N bond in the gaseous phase, this frequency is shifted to higher energy from 1575 to 1621 cm –1 (see below). A comparable rotation of the NO 2 group has been observed for NAP‐Cl 14b. All MNA salts show similar vibrational modes (except the N–H bands observed for 1 ), which can be assigned according to the literature 12.…”

3,3′‐Bi(1,2,4‐oxadiazoles) Featuring the Fluorodinitromethyl and Trinitromethyl Groups

“…For a practical use as energetic oxidisers the benchmark sensitivities are defined to be not higher than that of PETN (pentaerythrityl tetranitrate: impact sensitivity = 4 J, friction sensitivity = 80 N, ESD = 0.1 J). (11) 23.5680 (20) 9.4082 (8) 9.5775(8) a [8] 73.771 (15) 90.0 90.0 90.0 90.0 b [8] 85.568 (16) 102.936 (5) 102.758 (8) 100.985 (8) 100.459(9) g [8] 73.911 (14) 90.0 90.0 90.0…”

“…Although containing the halogen fluorine, materials containing this moiety usually show considerably higher thermal stabilities and lower sensitivities towards mechanical stimuli, but also lower heats of formation and oxygen balances, compared to their TNM analogues. [8,12] A new approach for the development of energetic oxidisers is the class of oxadiazoles-formally derived just by replacing the NH-group of any triazole derivative by an oxygen atom in order to increase the oxygen balance of these five-memberedring systems. A series of bifurazane (1,2,5-oxadiazoles) derivatives with trinitroethylamine and fluorodinitroethylamine substituents has been synthesised recently.…”

“…In the field of propellants and energetic oxidisers compounds with high oxygen balances Ω 8 are desired. They are required to provide oxygen to the actual fuel (Al) for its appropriate combustion in an oxygen‐poor or oxygen‐deficient environment 2.…”

“…Also the fluorodinitromethyl (FDNM) group is an interesting building block in analogy to TNM. Although containing the halogen fluorine, materials containing this moiety usually show considerably higher thermal stabilities and lower sensitivities towards mechanical stimuli, but also lower heats of formation and oxygen balances, compared to their TNM analogues 8. 12…”