Alkyl‐Bridged Nitropyrazoles – Adjustment of Performance and Sensitivity Parameters

Nitropyrazoles are famous powerful energetic materials. Herein we revisited the concept of alkyl-bridged nitropyrazoles to gain insight into structure-property relationships. The exchange of explosophoric functional groups and modification of alkyl-bridge length modifies the properties of the obtained energetic materials. The investigated compounds were synthesized in good yields and characterized exhaustively.

Abstract

Starting from 3,5-dinitro-4-methylaminopyrazole (2), six different energetic salts and three new derivatives of methylene bridged nitropyrazoles were synthesized. The derivatives bear a methylamino (4), methylnitramino (5), and azido group (7). All compounds were intensively characterized using single crystal X-ray diffraction, multinuclear NMR spectroscopy, IR spectroscopy, mass spectrometry, elemental analysis and DTA/TGA measurements. The sensitivities were determined according to BAM standard methods and the energetic properties calculated using the EXPLO5 code. The energetic salts were compared with each other and with ANTA in terms of their energetic properties. On the basis of the methyl- and ethyl bridged derivatives, it was shown how the introduction of methylamino (4) and methylnitramino (5) groups in an alkyl-bridged nitropyrazole system modify its properties (performance & sensitivities). In addition, azido compound 7 was contrasted with its literature-known constitutional isomer and investigated for its suitability as a potential metal-free primary explosive.

Zum Volltext