Synthesis and thermal decomposition of 15N-labelled NTO

5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) has been synthesized in good yield with 15N at the 1 and 2 positions. The N-H coupling provides unequivocal assignments for 1H and 15N NMR spectra and the acidic proton. The products of thermal decomposition at 270 °C were identified spectroscopically. NMR spectra reveal that thermal decomposition results in the formation of 2,4-dihydro-3H-1,2,4-triazol-3-one and ammonia (the latter observed as ammonium ion). The production of ammonia from the thermal decomposition of an energetic material is unprecedented. The gas products HCN, 15N14N, 15N2 and CO were detected by mass spectrometry. Some possible mechanisms of thermal decomposition are discussed.