Energetic derivatives of 4,4′,5,5′-tetranitro-2H,2′H-3,3′-bipyrazole (TNBP): synthesis, characterization and promising properties

Abstract

4,4′,5,5′-Tetranitro-2H,2′H-3,3′-bipyrazole (TNBP, 1) is an excellent precursor to new energetic derivatives (3 and 5–14). The monotrinitromethyl substituted compound (3) was obtained by alkylation with bromoacetone and subsequent nitration. Nitration of the aminated compound (4) with nitronium tetrafluoroborate (NO₂BF₄) in the presence of potassium acetate results in the monopotassium salt (5). Dianionic salts of 1 with potassium and nitrogen rich cations (6–14) were prepared by neutralization. These compounds were fully characterized using NMR and infrared spectra and elemental analyses as well with single crystal X-ray diffraction for 3, 5, 8 and 10. The detonation properties, determined from the calculated heats of formation and measured densities, show that some (3, 7 and 13) are superior to those of 1,3,5-trinitrotriazacyclohexane (RDX). In addition, given the high thermal stability (323 °C) and good detonation performance of 6, it could be a promising green primary explosive.