1,1-Diamino-2,2-dinitroethene (FOX-7) and 1-amino-1-hydrazino-2,2-dinitroethene (HFOX) as amphotères: bases with strong acids

Abstract

The exciting discovery of the first cations based on 1,1-diamino-2,2-dinitroethene (FOX-7) and its hydrazine derivative, 1-amino-1-hydrazino-2,2-dinitroethene (HFOX), along with their syntheses and full characterization is described. The oxygen rich content of these cations lends to their potential as promising precursors for energetic salts. A variety of acids including triflic, perchloric, and hydrochloric acids were found to react with FOX-7 and HFOX to give rise to the following salts: 1-amino-2,2-dinitroethaniminium triflate (3a), 1-amino-2,2-dinitroethaniminium perchlorate (3b), 1-amino-1-hydrazino-2,2-dinitroethaniminium triflate (4a), and 1-amino-1-hydrazino-2,2-dinitroethaniminium chloride (5). Additionally, it was also found that HFOX reacts with acetone to generate the corresponding hydrazone derivative, 2,2-dinitro-1-(2-(propan-2-ylidene)hydrazinyl)ethenamine (9). The structures of the salts (except 5) and hydrazone 9 are supported by single crystal X-ray analysis. These compounds have thermal stabilities ranging between 74–147 °C and crystal densities between 1.53 g cm⁻³ to 1.94 g cm⁻³. The isolation of these novel FOX-7 and HFOX cations are interestingly important as it: (1) extends the chemistry of FOX-7 and HFOX, (2) demonstrates the amphoteric properties of FOX-7 and HFOX, and (3) gives rise to new forms of FOX-7 and HFOX, which opens the study of their potential as promising precursors for energetic salts. All the salts were found to have energetic properties that exceed that of TNT and some are comparable to FOX-7 and RDX, indicating that the cations of FOX-7 and HFOX may contribute to more energetic salts if parlayed with appropriate counter anions. The significance of this work demonstrates that the chemistry of FOX-7 continues to be profound and worthwhile.