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

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.