Three New Compounds Based on 4,4′-Azo-1,2,4-triazol-5-one: Synthesis, Crystal Structure and Thermal Properties

A series of guanidine salts of 4,4'-azo-1,2,4-triazol-5-one with guanidine(1), aminoguanidine(2), diaminoguanidine(3) and triaminoguanidine(4) was prepared. Compounds 2-4 were characterized by infrared(IR) spectroscopy, elemental analysis and single-crystal X-ray diffraction. Thermal decomposition processes of compounds 1-4 were investigated by differential scanning calorimetry(DSC), and all the compounds showed good thermal stability up to 190 degrees C. Moreover, these four guanidine salts are more unstable with the increasing number of amino groups. Thermal stability parameters(T-e,T-0 and T-b) and thermodynamic functions(Delta S-not equal , Delta H-not equal and Delta G(not equal)) for compounds 1-4 were calculated. The constant-volume combustion heats(Delta U-c) for compounds 2-4 were determined and tended to increase with the increase of the number of amino groups. The calculated standard molar enthalpies of formation(Delta H-f(m)0) of compounds 2-4 are -541.04, -178.67 and -83.08 kJ/mol, respectively. The impact sensitivities results indicate that these four energetic salts are less sensitive than 1,3,5-trinitrotriazacyccohexane(RDX) and 1,3,5,7-tetranitrotetraqza-cyclo-octane(HMX).