Study on a Novel Synthetic Route and Properties of 1‐trinitromethyl‐3‐nitro‐1,2,4‐triazole (TNMNT)

Abstract

Materials with low melting point and high energy density have become the focus of research on energy‐containing materials thanks to their superb detonation performance and wide applications. This paper proposed a new synthetic route for an energy‐containing compound 1‐trinitromethyl‐3‐nitro‐1,2,4‐triazole (TNMNT), using 3‐nitro‐1,2,4‐triazole as the raw material, low toxic chloroacetone as the substitute and KBr as the catalyst. These substances reacted at 70 °C for 3 h in a DMF reaction solvent system. The intermediate 1‐acetonyl‐3‐nitro‐1,2,4‐triazole (ANT) was obtained with a yield of 38 %. The nitration process increased the volume ratio of mixed nitric and sulfuric acids (1 : 3), and the reaction time was 36 h. TNMNT as a nitrogen‐rich compound having low melting point and high energy density was synthesized with a yield of 43 %. Compared with the traditional process, the experimental period was significantly shortened, and this synthetic method proved more environment‐friendly. Scanning Electron Microscopy (SEM), Differential Scanning Calorimeter (DSC) and mechanical sensitivity tests were performed on the products. It was found that the melting and decomposition points of TNMNT were 100.5 °C and 166.4 °C, respectively, the characteristic drop height H50 was 21.3 cm, and the frictional sensitivity was 56 %. Results show that the TNMNT crystals synthesized by this new route have better morphology, higher purity, and lower melting point. Compared with the raw material, the introduction of the trinitromethyl group produced higher mechanical sensitivity than other compounds having low melting point. Calculation of the thermal decomposition parameters found: activation energy of 104.4 kJ ⋅ mol−1, pre‐exponential factor of 2.27×1010 s−1, activation enthalpy of 100.9 kJ ⋅ mol−1, activation entropy of 57.98 J ⋅ mol−1 ⋅ K−1, and activation free energy of 125.72 kJ ⋅ mol−1.