Synthesis and thermal decomposition of N-15-labelled NTO

5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) has been synthesized in good yield with N-15 at the 1 and 2 positions. The N-H coupling provides unequivocal assignments for H-1 and N-15 NMR spectra and the acidic proton. The products of thermal decomposition at 270 degrees 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, (NN)-N-15-N-14, N-15(2), and CO were detected by mass spectrometry. Some possible mechanisms of thermal decomposition are discussed.