Synthesis, crystal structure and thermal behaviors of 2,3-dihydro-4-nitro-3-(dinitromethylene)-1H-pyrazol-5-amine potassium salt [K(NNMPA)]

A novel high-energy organic potassium salt, 3-(dinitromethylene)-4-nitro-2,3-dihydro-1H-pyrazol-5-amine potassium salt [K(NNMPA)], was first synthesized by an unexpected reaction of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and KOH in methanol aqueous solution. K(NNMPA) was characterized by elemental analysis, IR spectra, 13C NMR and single-crystal X-ray diffraction. K(NNMPA) crystallized in monoclinic system, space group P21/c with crystal parameters of a = 9.358(3) Å, b = 13.079(4) Å, c = 7.568(2) Å, β = 107.344(5)°, V = 884.2(5) Å3, Z = 4, μ = 0.638 mm−1, F(0 0 0) = 544 and Dcalc = 2.03 g cm−3. Thermal decomposition of K(NNMPA) was studied with DSC and TG-DTG methods and presents two exothermic decomposition processes. The kinetic equation of the first process obtained is d α dT = 10 18.42 β 4 ( 1 - α ) [ - ln ( 1 - α ) ] 3 / 4 exp ( - 1.665 × 10 5 / RT ) . The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) of K(NNMPA) are 137.4 and 146.3 °C, respectively. K(NNMPA) exhibits lower thermal stability than K(AHDNE).