Synthesis, characterization and thermolysis of polynitrohexahydropyrimidines: potential high energy materials

Abstract

A relatively new entrant to the class of high energy materials, viz., 1,3,5-trinitro-5-methyl-hexahydropyrimidine (MTNP) has been synthesized during this work by nitration of 1,3-di-tert-butyl-5-nitro-5-methyl hexahydropyrimidine with fuming nitric acid. The synthesized molecule (MTNP) has been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy. TG of the compound showed two-step decomposition in the temperature range of 170-200°C and 205-350°C accompanied with 50 and 25% weight loss, respectively. The sensitivity data of MTNP obtained for the synthesized compound indicates its low vulnerability towards external stimuli (impact height, h_50% > 100 cm and friction insensitive up to 36 kg). The velocity of detonation of MTNP has been computed using Linear Output Thermodynamic User-friendly Software for Energetic Systems (LOTUSES) code. The theoretically computed VOD of 7450 m/s is intermediate to that of 2,4,6-trinitrotoluene, TNT (6600 m/s) and 1,3,5-triamino-2,4,6-trinitrobenzene, TATB (7860 m/s) coupled with insensitive nature are attractive features from the point of view of its applications in insensitive munitions. In addition to compound MTNP, synthesis and characterization of some of the promising polynitrohexahydropyrimidines have also been reported.