Synthesis and thermal stability of mercury diacetylide Hg(CCH)2

Mercury diacetylide was synthesized and studied by FT-IR spectroscopy, both in the mid and far infrared, and electronic absorption spectroscopy. The spectral data are consistent with the structure H-CC-Hg-CC-H. Mercury diacetylide is insoluble in common solvents but shows a minimal solubility in ethanol and tetradecane. The thermal stability of mercury diacetylide was studied by thermogravimetry (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). In an open crucible under nitrogen, mercury diacetylide undergoes an exothermal and explosive decomposition releasing 725.6 J/g with an onset temperature of about 250 °C and a peak temperature of 287 °C. The decomposition occurs at a higher temperature in a sealed crucible (onset 326 °C and peak 337 °C). Using the TGA-FT-IR analytical technique it has been found that the deflagration of mercury diacetylide produces elemental carbon, elemental mercury and acetylene. The enthalpy of formation of mercury diacetylide has been determined for the first time. The explosive parameters of mercury diacetylide have been compared with those of other common explosives showing that it is a dangerous and powerful explosive.