Novel 4,5‐Dinitro‐N,N′‐dialkylimidazolium Cations as Candidates for High‐energy Materials

Abstract

In the synthesis of energetic ionic liquids (EILs), the quaternization of dinitroimidazoles remains a challenging task due to their reduced nucleophilicity. In this study, two new EILs precursors, 3‐ethyl‐1‐methyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium tetrafluoroborate (1) and 1,3‐diethyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium tetrafluoroborate (2) were obtained via the alkylation of 1‐methyl‐4,5‐dinitro‐1H‐imidazole and 4,5‐dinitro‐1H‐imidazole using Meerwein's reagents, respectively. The 4,5‐dinitroimidazolium cations are expected to be applied for new insensitive high‐energy materials (HEMs) via an anion metathesis reaction with energetic anions. Two new EILs, 3‐ethyl‐1‐methyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium 2,4,5‐trinitroimidazol‐1‐ide (3) and 1,3‐diethyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium 2,4,5‐trinitroimidazol‐1‐ide (4), were obtained as potential HEMs via the anion metathesis reaction with 2,4,5‐trinitroimidazol‐1‐ide. Although some improvements in the thermal properties are desired, compound 3 showed the promising properties as a new insensitive HEM because of its excellent insensitivity and more powerful explosive performance than those of 2,4,6‐trinitrotoluene (TNT).