Selection and synthesis of energetic heterocyclic compounds suitable for use in insensitive explosive and propellant compositions

The rationale behind developing insensitive energetic compounds (IECs) for incorporation into insensitive munition (IM) formulations (rather than the alternative approach of desensitizing higher energy but sensitive compounds) is discussed. With the aim of selecting a maximum of 2-3 IECs suitable for use in insensitive explosive and propellant compositions, a survey of the literature on IECs published in the last 20 years was carried out. From around 50 candidates, a selection was made of eight prime candidates, all heterocyclic compounds (principally monocyclic or fused-ring bicyclic compounds of the di- or triazine, triazole or oxadiazole classes), which displayed explosive performance significantly better than that of the ubiquitous IEC, TATB. The criteria for inclusion of compounds in these listings are described. Screening of the eight candidate compounds against further performance criteria reduced the list to five compounds which were evaluated in detail - these were: CL-14 (5,7-diamino-4,6-dinitrobenzofuroxan), ANPZ-i (2,5-diamino-3,6-dinitropyrazine), NNHT (2-nitrimino-5-nitro-hexahydro-1,3,5-triazine), NTAPDO (5-nitro-2,4,6-triaminopyrimidine-1,3-dioxide), and PANT [4-(picrylamino)-5-nitro-1,2,3-triazole]. A detailed analysis of scale-up issues associated with each compound was then made, including cost and availability of precursors, hazards (chemical and explosive), effluent streams, and other scale-up issues (e.g. materials of plant construction). A further downselection using these criteria gave the present short-list comprising three compounds (the first three listed above) and further evaluation is in progress. The results of this study, funded by UK MOD, comprise the UK contribution to a nine-nation European research collaboration in the EUCLID Common European Priority Area 14 Energetic Materials, as part of a five-year project which commenced in October 2003.