Advancing green primary explosive design: A methyl-driven strategy for aromaticity modulation and safety enhancement

Abstract

The synthesis of conventional organic primary explosives poses significant safety challenges. A novel strategy for designing primary explosives has been developed, featuring the incorporation of a non-energetic methyl group into a fused ring system. This approach enabled the safe and efficient preparation of 2-methyl-4,7-nitroamino-1H-imidazo[4,5-d]pyridazine (MNIP), a compound demonstrating considerable potential as a primary explosive. MNIP demonstrates good energetic performance and enhanced safety parameters (ν = 7710 m·s -1 ; FS = 120 N), outperforming the classical organic primary explosive DDNP. Theoretical and experimental analyses reveal that the methyl group effectively modulates the aromaticity of the fused ring system and weakens intermolecular hydrogen bonding interactions, resulting in enhanced sensitivity characteristics. Furthermore, energetic salts derived from MNIP were synthesized and characterized, exhibiting favorable thermal stability (T_d ≥ 185 ℃) while maintaining appropriate impact sensitivity (< 2 J). Synthesis of MNIP is efficient and economical in terms of material costs, suggesting its considerable potential as a next-generation metal-free primary explosive for practical use.